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**Chuck73080** · 06-26-2022, 04:12 AM

DoubleL,

I have gone thru some of the same pondering that you are experiencing, only my truck is a '66 C30 Cab and Chassis, 157" WB, 283, SM420, HO72 DRW/5.13. I bought my truck last year with 66,000 original miles and the Cab was restored five years prior. A custom built 10' FB was also installed.

I want to pull a 5th wheel camping trailer and travel (retired), So I called GV and was quoted $3,600 for the unit plus installation.

So, as I see it, here are your choices:

If you are happy with the 283 and SM420 the cheapest thing is to find a '67-72 C20 Dana 60 SRW, a '73-88 14 bolt will drop in also. I'll let you do the homework. But either '68 or '69 offered a Dana 60 3.54 ratio when the 396 engine was ordered.

Here is a link to the GM Heritage Center page for info on all GM trucks 1934-2007, Be careful of the rabbit hole you may step into. I've had some very late nights in those pages.

https://www.gmheritagecenter.com/gm-...tion-kits.html

Here is a link to a cool Spicer RPM calculator:

https://spicerparts.com/calculators/...rpm-calculator

I've now bought two of these axles (long story), the first was a Dana 60 7600# DRW 3.54 ratio with posi. for $1150 and the second was a '67 Dana 60 14,000# DRW 6.13 ratio for $750. Summit quoted $2.200 in parts to replace everything inside for a 3.54 posi. outcome. (local 4WD shop quoted $2,300 parts and labor).

OK second option:

If you are thinking of an AT, the 700R4 .70 OD would turn your 4.57 into 3.199. In my truck running 225/75R16 tires @ 29.3" dia. = 2751 RPM@75MPH.

The GV .78 OD would give you a final ratio of 3.5646 or 3066 RPM@75MPH in my truck.

Or choice #3:

Buy a TREMEC TR-4050 6.16, 3.11, 1.71, 1.00, 076 Rev. 6.03. My quote from Silver State Transmissions was $4,389.21 with a shifter, mechanical clutch linkage and bellhousing (Mandatory- the bolt pattern on trans is not GM and the runout clearances are very tight)

They were original equipment in 2006-2007 F550 trucks.

Watch this YouTube video:

https://www.youtube.com/watch?v=srnhgs6OV-Y

There are other trans. but they are truck transmissions and I wanted a fast shifting sporty transmission that can handle my 396 SBC 535HP/506 TQ (Dyno sheet). It is rated 600 lb/ft torque and is quick shifting.

https://flickr.com/photos/4-5-6chevy...7653616824764/
https://flickr.com/photos/4-5-6chevy...7653616824764/

https://www.youtube.com/watch?v=Dx_8fwfkEfU&t=123s
This video is not an endorsement of 4-5-6 Chevy Trucks in any way, shape or form. he just shot the video.

06-26-2022, 04:12 AM	#9
Chuck73080 Registered User Join Date: Jan 2021 Location: Purcell, OK 30 miles south of OKC Posts: 24	Re: 1965 C20 new to me DoubleL, I have gone thru some of the same pondering that you are experiencing, only my truck is a '66 C30 Cab and Chassis, 157" WB, 283, SM420, HO72 DRW/5.13. I bought my truck last year with 66,000 original miles and the Cab was restored five years prior. A custom built 10' FB was also installed. I want to pull a 5th wheel camping trailer and travel (retired), So I called GV and was quoted $3,600 for the unit plus installation. So, as I see it, here are your choices: If you are happy with the 283 and SM420 the cheapest thing is to find a '67-72 C20 Dana 60 SRW, a '73-88 14 bolt will drop in also. I'll let you do the homework. But either '68 or '69 offered a Dana 60 3.54 ratio when the 396 engine was ordered. Here is a link to the GM Heritage Center page for info on all GM trucks 1934-2007, Be careful of the rabbit hole you may step into. I've had some very late nights in those pages. https://www.gmheritagecenter.com/gm-...tion-kits.html Here is a link to a cool Spicer RPM calculator: https://spicerparts.com/calculators/...rpm-calculator I've now bought two of these axles (long story), the first was a Dana 60 7600# DRW 3.54 ratio with posi. for $1150 and the second was a '67 Dana 60 14,000# DRW 6.13 ratio for $750. Summit quoted $2.200 in parts to replace everything inside for a 3.54 posi. outcome. (local 4WD shop quoted $2,300 parts and labor). OK second option: If you are thinking of an AT, the 700R4 .70 OD would turn your 4.57 into 3.199. In my truck running 225/75R16 tires @ 29.3" dia. = 2751 RPM@75MPH. The GV .78 OD would give you a final ratio of 3.5646 or 3066 RPM@75MPH in my truck. Or choice #3: Buy a TREMEC TR-4050 6.16, 3.11, 1.71, 1.00, 076 Rev. 6.03. My quote from Silver State Transmissions was $4,389.21 with a shifter, mechanical clutch linkage and bellhousing (Mandatory- the bolt pattern on trans is not GM and the runout clearances are very tight) They were original equipment in 2006-2007 F550 trucks. Watch this YouTube video: https://www.youtube.com/watch?v=srnhgs6OV-Y There are other trans. but they are truck transmissions and I wanted a fast shifting sporty transmission that can handle my 396 SBC 535HP/506 TQ (Dyno sheet). It is rated 600 lb/ft torque and is quick shifting. https://flickr.com/photos/4-5-6chevy...7653616824764/ https://flickr.com/photos/4-5-6chevy...7653616824764/ https://www.youtube.com/watch?v=Dx_8fwfkEfU&t=123s This video is not an endorsement of 4-5-6 Chevy Trucks in any way, shape or form. he just shot the video. __________________ Chuck73080 R.I.P. Dad 1/6/1928 to 12/1/2020 Last edited by Chuck73080; 06-27-2022 at 12:34 AM. Reason: Add pics