Upgrade to 5 speed manual

[tucsonjwt]

I have a 1983 C20 454 BB with SM465 granny 4 speed with a gear vendor. The gear vendor is shot and the transmission is leaking from the front (although it still shifts OK.)

Rather than get a reman Gear Vendor and have the granny 4 speed rebuilt, I am considering having a modern 5 speed manual transmission installed.

What would you guys recommend for a transmission upgrade with minimal modification required. I will have to get a new driveshaft to replaced the shortened drive shaft for the Gear Vendor. i am looking for a 5 speed that might bolt up to the 454 BB I have without an adapter, or at least a low cost adapter that is not a cobbled together contraption.

A reman Gear Vendor with a new control unit is about $2K ($1250 for the GV unit, $400 for the control box, $120 for shipping with my core + labor to R &R.)

[csdineley]

Nv4500

[kipps]

An nv4500 is really the only reasonable bolt-in five speed option. There's several routes you can go.

Use a 92-95 nv4500 with your existing bellhousing. You'll need to drill and tap the face of the transmission to accept bolts, and the bolts will be installed from inside the bellhousing. The clutch linkage will remain exactly the same as it currently is.

Use a 92-95 nv4500 with its stock bellhousing. You'll need to use the clutch pedal and clutch master cylinder from a 85-87 truck. This will connect to an external slave down low on the passenger side of the 92-95 nv4500 bellhousing.

Use a 96-07 nv4500 with its stock bellhousing and internal slave. This will require the clutch pedal and master cylinder conversion as well.

Use any nv4500 with an Advance Adapters aftermarket bellhousing. These should allow your stock mechanical linkage. Contact Advance Adapters for specific fitment details.

A nv3500 will fit very similarly, but it's definitely not recommended for big block torque outputs.

[mongocanfly]

another vote for the NV

[SunSoaked]

I just converted my K20 from auto to an NV4500 this weekend. It's not for the faint of heart! It's time consuming, expensive and a PITA!

However, that trans shifts like butter and I can actually drive it on the highway now.

If you have any questions, I have lots of answers....and parts.

[SunSoaked]

This.

[kipps]

Sunsoaked, do you have any internal parts that would be available for cheaper than new? I'm needing the 51-tooth fifth gear and the GM input shaft/gear. Both of mine got chipped from a trashed thrust bearing sending metal fragments through the case. I'm seeing prices of about $100 for each gear, depending on the source. I also need the 3/4 synchro hub. Mine is grooved pretty deep from that failed thrust bearing.

Tucsonjwt, definitely remove the tailhousing from any nv4500, and confirm that fifth gear is still where it's supposed to be. Particularly if the transmission was behind a diesel engine. Mine was out of place, and was only halfway engaged with the countershaft fifth gear. I'm still trying to decide how extensively I'll pursue fixing/preventing the problem.

[mongocanfly]

Keep in mind there is a early and late version of the NV....sunsoakeds is the early version..the late version has the bolt on shift tower..

[SunSoaked]

Kipps,
I don't have any actual trans parts. Like Mongo said, I have the early version. However, the top plate and shifter (as a package) all interchange. My spare 94 trans has the late removable shifter. The later ones have shorter throws and removable towers.

[kipps]

Originally Posted by SunSoaked

Kipps,
I don't have any actual trans parts. Like Mongo said, I have the early version. However, the top plate and shifter (as a package) all interchange. My spare 94 trans has the late removable shifter. The later ones have shorter throws and removable towers.

yeah, I'm working with a later style. It was sold to me as a 98, but I think that 98 would have to have a synchronized reverse. Upon disassembly, I realized my reverse is definitely not synchronized. I'm suspecting it's a 1997, since it does have the 97+ reverse ratios.

[1976gmc20]

A nv3500 will fit very similarly, but it's definitely not recommended for big block torque outputs.

Having an NV3500 (or equivalent) in my 89 K1500, I wouldn't recommend it for anything.

[kipps]

Originally Posted by 1976gmc20

Having an NV3500 (or equivalent) in my 89 K1500, I wouldn't recommend it for anything.

You know, a 92-95 nv4500 would be an exact drop-in replacement for your nv3500. Same shifter location, slave location, input & output shaft size, and transfer case mount.

The 92-94 nv4500's will have a granny gear, which you likely don't want. The 95 will be much closer to the gearing you're used to already. In 96, they switched to internal slaves, which will no longer be an exact bolt-in swap into your truck.

[1976gmc20]

Originally Posted by kipps

You know, a 92-95 nv4500 would be an exact drop-in replacement for your nv3500. Same shifter location, slave location, input & output shaft size, and transfer case mount.

The 92-94 nv4500's will have a granny gear, which you likely don't want. The 95 will be much closer to the gearing you're used to already. In 96, they switched to internal slaves, which will no longer be an exact bolt-in swap into your truck.

That's what I will do, if and when my 5 speed fails - unless I just decide to junk the pickup instead and get something else in 3/4 or 1 ton.

Actually, the granny gear is exactly what I want! I'm tired of having to put my pickup in low range any time I want to creep around or back up.

Thanks for the information. Somehow I thought that it was more complicated. I guess the complicated part is finding a good 4500 in the right years without costing too much.

[tucsonjwt]

Thanks for all of the input.

I will not be doing the work myself, so hired labor will be a factor in deciding which way I should go.

If I put a NV4500 in i will have to get a new driveshaft made for about $700.

It seems like getting the correct NV4500 for my truck would be the main issue.

Ballpark estimate for a NV4500 rebuild is $2K + the cost of a core (if I can find one.)

The local Gear Vendor mechanic recommended a NV4500, but he will not hunt down the correct NV4500 or do the necessary mods. He did say that a new Gear Vendor could be installed with just an on/off switch which would control the power supplied to the shifter mounted engage/disengage button, so that would eliminate the $400 control box. The control box is supposed to prevent engaging the Gear Vendor below 25 mph, but I don't think it ever worked properly in my truck anyway. That would put the reman Gear Vendor at $1250 + $120 shipping + California tax.

I am leaning toward having the SM465 and gear vendor removed and taken to a a local transmission shop for a repair estimate. If that estimate is not too high and includes a sloppy shifter fix, that might be the cheapest way out.

Does anyone have ideas on how to repair the sloppy shifter on the SM465? I don't want a fix which involves welding the shifter to the extent that i end up with a shifter rattling in 4th gear - I would rather have a sloppy shifter than that. I had a 63 SWC Corvette with a 4 speed where the previous owner welded the shifter and I had the 4th gear shifter rattle - very annoying.

When the gear vendor is not engaged and working and I drive on the highway, the 454 is running at very high RPMs since I have a 4:10 rear end. The gear vendor is supposed to reduce the final rear axle ratio by 20%, so that is like have a 3:23, which is a nice highway gear - effectively an overdrive.

[57NAPCO]

My vote would be the GV , I’m looking to do the same with 2 trucks I have with SM 465’s.

[tucsonjwt]

Thanks 57. Having the core gear vendor in the truck does allow for a cheaper reman GV unit, since the core brings the reman price down to $1250 instead of about $3150 + tax and shipping for a new one with all the accessories needed.

When I talked to Dave at Gear Vendors he said they do not market their GV units to truck owners since most truck owners now have modern automatics with multiple gears, or a few have 5 speed or 6 speed transmissions which don't benefit much from a Gear Vendor. They focus on the hot rod market.

On the other hand, I see Gear Vendor adapters and used GV units selling for high prices (likely for the core value) on Ebay - so that swings the needle toward the NV4500 swap, if I can recover some cost in selling the used pieces I have. Hard to decide on this one.

[44th Miss Inf]

You can pick up NV4500s reasonable still with some shopping around. I picked up a 95 2wd one with 20k on rebuild (included paperwork from trans shop) for $350. I was offered $225 for the bell housing (which I didn’t need) so have $125 in that one.
First of Dec saw one advertised as a “98 NV3500 with t-case” that was actually an NV4500. I inquired about the trans and bought it for $400 as they had sold the transfer case already. That trans has 3-5k already on it in a buddy’s truck with no issues or noises.

They are out there for reasonable prices if you can hold out and wait

[mongocanfly]

I wish I coulda found them that cheap 44th... when I bought mine I looked all over for a NV and couldnt find anything reasonable...they wanted more for the pullout trans than what the core charge was at the trans shop that I bought the new rebuilts from..so I paid the core charge..

[1976gmc20]

Originally Posted by 44th Miss Inf

You can pick up NV4500s reasonable still with some shopping around. I picked up a 95 2wd one with 20k on rebuild (included paperwork from trans shop) for $350. I was offered $225 for the bell housing (which I didn’t need) so have $125 in that one.
First of Dec saw one advertised as a “98 NV3500 with t-case” that was actually an NV4500. I inquired about the trans and bought it for $400 as they had sold the transfer case already. That trans has 3-5k already on it in a buddy’s truck with no issues or noises.

They are out there for reasonable prices if you can hold out and wait

I guess that I should just look for and buy a 92-95 nv4500 and store it until I need it.

Heck, might as well get one with the TC.

[kipps]

Originally Posted by 1976gmc20

Heck, might as well get one with the TC.

Remember that the nv4500 never came with a passenger side transfer case. You'll need to connect it to a driver's side transfer case, unless you're also doing a Ford d44 or d60 front axle swap.

[1976gmc20]

Originally Posted by kipps

Remember that the nv4500 never came with a passenger side transfer case. You'll need to connect it to a driver's side transfer case, unless you're also doing a Ford d44 or d60 front axle swap.

Sorry, I know this is the wrong forum ... somebody said something about the nv3500 and I agreed that was not a good choice, as I have that in my 1989 K1500.

So an nv4500 and t/c will drop right into my pickup

Originally Posted by 1976gmc20

Having an NV3500 (or equivalent) in my 89 K1500, I wouldn't recommend it for anything.

[kipps]

Originally Posted by 1976gmc20

So an nv4500 and t/c will drop right into my pickup

Oh, Woops. Sorry about that. I forgot who I was replying to. All's good!

Although, your current transfer case is likely identical to what was used on k2500 trucks(equipped with the nv4500) of the same era. Both of them are 32-spline, the driveshaft slip yoke size is almost certainly the same size, and they are probably both np241c cases as well.

[1976gmc20]

Originally Posted by kipps

Oh, Woops. Sorry about that. I forgot who I was replying to. All's good!

Although, your current transfer case is likely identical to what was used on k2500 trucks(equipped with the nv4500) of the same era. Both of them are 32-spline, the driveshaft slip yoke size is almost certainly the same size, and they are probably both np241c cases as well.

Transmission and t/c are both working okay for now, but this pickup has had a hard life so you never know. I bought it from a lady after a divorce. He was a jerk.

[cadillac_al]

A guy wrote in to Four Wheeler magazine saying he put a nv4500 in a 70's K20 to replace a sm465 and it was an easy bolt in swap. He said it couldn't have been any easier. I made a mental note in case a sm465 truck finds it's way into my stable.

[57NAPCO]

Thanks for the heads up, still looking for the article but found this in the meantime....


https://www.fourwheeler.com/how-to/t...e-square-body/

Originally Posted by cadillac_al

A guy wrote in to Four Wheeler magazine saying he put a nv4500 in a 70's K20 to replace a sm465 and it was an easy bolt in swap. He said it couldn't have been any easier. I made a mental note in case a sm465 truck finds it's way into my stable.