67 12-bolt to SM 465 Transmission

[Rich1972C20]

Guys,

I'm looking for a cost effective/easy solution to mate my SM465 to 12-bolt axle.

I swapped in a 350cuin/sm465 in my '67 C-10 which had a 6 cylinder SM418. Obviously the driveshafts don't match. The 350/SM465 came out of 72 C-20 with Dana 60 axle. The 72 driveshaft has a much larger diameter and different mounting arrangement than the 67 (see photos). As I see it the options I have are as follows:

1) Custom driveshaft. My concern here is can the 12-bolt handle the added torque (about 400ft/lbs)?

2) Swap out the axle with one that is compatible with the Dana 60/SM465 configuration (did chevy make this?). I would use the axle from the '72 but it is a leaf spring suspension (my 67 is trailing arms) and it has 8 lug bolt axles. Also not sure if the axle length is compatible with my '67 configuration.

3) Put in a different 4/5 speed transmission that I can use with my current axle.

Bonus question, if I can use my current 12-bolt axle can I make it a posi? I believe that there is a difference between a passenger car 12-bolt vs a truck.

[mr48chev]

You should be able to buy a "combination joint to mate the yoke on the transmission to the drive shaft. That would be the simple way. Then you can keep the original drive shaft and carrier.

The original rear axle is plenty strong enough if you aren't prone to revving the engine up to 5 grand and sliding your foot off the clutch to do burnouts with the new power. Or decide that now that you have the new power you can stick it in Granny and pull that stump out that your wife has been fussing about. Abuse usually breaks parts rather than torque and horsepower.

[Rich1972C20]

Thanks. Is the combination joint you mention the same as a cardan joint?

Can I put posi in this truck 12-bolt?

Thanks agin.

[57taskforce]

You can absolutely put a Posi in the truck 12. There are several to choose from. The conversion joint just has one series of u joint on one side and a different series on the other if that makes sense. Not the same as a double cardan.

[dmb]

that joint is called a dog joint, you may have to get an old parts guy to find it though.
The weak link in your drive train will be that 2-piece drive shaft.

[54blackhornet]

Having your drive shaft properly engineered is money well spent.

[Rich1972C20]

Thanks guys.

I'm bring the driveshafts to a driveshaft specialist.

Since this is a long bed do you recommend converting it to a one-piece driveshaft?

Lastly, there is rust and pitting on the shafts. Is it common to replace the whole shaft because of this? I wouldn't say the rust is excessive but I just want to be prepared.

Thanks!

[Accelo]

I'm looking for a cost effective/easy solution to mate my SM465 to 12-bolt axle.

I swapped in a 350cuin/sm465 in my '67 C-10 which had a 6 cylinder SM418. Obviously the driveshafts don't match. The 350/SM465 came out of 72 C-20 with Dana 60 axle. The 72 driveshaft has a much larger diameter and different mounting arrangement than the 67 (see photos). As I see it the options I have are as follows:

1) Custom driveshaft. My concern here is can the 12-bolt handle the added torque (about 400ft/lbs)?
Doubt you will any issues with the torque. Running 12-inch wide tires and driving like you are 16 it's possible to mess up anything. Reasonable anything and it will work.

2) Swap out the axle with one that is compatible with the Dana 60/SM465 configuration (did chevy make this?). I would use the axle from the '72 but it is a leaf spring suspension (my 67 is trailing arms) and it has 8 lug bolt axles. Also not sure if the axle length is compatible with my '67 configuration.
Way too much work and their are easier solutions.

3) Put in a different 4/5 speed transmission that I can use with my current axle.
Again way too much cost and work and their are easier solutions.

Bonus question, if I can use my current 12-bolt axle can I make it a posi? I believe that there is a difference between a passenger car 12-bolt vs a truck.
Yes you can make it a Posi. If you don't change the gear ratio it's not a bad job. Yes the car and truck twelve bolts are not the same.

Lastly, there is rust and pitting on the shafts
Same as answer #1. (Doubt you will any issues with the torque. Running 12-inch wide tires and driving like you are 16 it's possible to mess up anything. Reasonable anything and it will work.) Lots of cleaning will likely tell you it's just pitting? Best guess using pictures and some experience.
Cheers

[Rich1972C20]

Thanks guys. Much appreciated