Click on image for the lowdown. 
====
| | | Forums66 Topics128,048 Posts1,055,664 Members48,426 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | 
#28314 10/25/2002 5:14 PM | Joined: Apr 2000 Posts: 28 'Bolter | | 'Bolter Joined: Apr 2000 Posts: 28 | I am currently doing a ground up on a 51 3800 pickup (chevy) and im now at the point where i have to make some decisions. i am going with a 235, updating the rear to 3.90 and need some advice on what tranny to go with.Any help or advice would be greatly appreciated. | | |
#28315 10/25/2002 7:08 PM | Joined: Jun 2000 Posts: 2,773 'Bolter | | 'Bolter Joined: Jun 2000 Posts: 2,773 | First, what are you going to do with the truck? What kind of driving? Parades, highway, drag strip, bouncing around the pasture?
Fred
52 3600
69 C-10
| | |
#28316 10/26/2002 3:24 AM | | Anonymous Unregistered | | Anonymous Unregistered | a one ton truck deserves nothing less than a 4 speed. SM420. | | |
#28317 10/26/2002 5:56 AM | Joined: Dec 2001 Posts: 1,745 Member | | Member Joined: Dec 2001 Posts: 1,745 | If you are upgrading the rear anyway, can you go more than 3.90?
54 3100 with 235
62 flatbed dump C60 with 261
| | |
#28318 10/26/2002 7:50 PM | Joined: Mar 2001 Posts: 316 Member | | Member Joined: Mar 2001 Posts: 316 | What's wrong with 3.90's ? I think that's an excellent choice. Beats the heck out of the stock 4.57's, at least for seeing some highway duty. If it's just going to be beating around the property, than just leave the stock gears in. Just be glad you don't have 6.13's !  3500 RPM at 63 mph with 37" tall tires. If you know what tires you'll be running, go to this site . That should help clear up your decision. Good Luck Phil, whatever you decide  .
*** GMC ***
| | |
#28319 10/28/2002 11:05 PM | Joined: Apr 2000 Posts: 28 'Bolter | | 'Bolter Joined: Apr 2000 Posts: 28 | Not looking to haul any weight at all, mostly, truck will be used as a driver. Is the sm 420 an easy bolt in, or would there be mods? | | |
#28320 10/29/2002 5:54 AM | Joined: Jun 2000 Posts: 2,773 'Bolter | | 'Bolter Joined: Jun 2000 Posts: 2,773 | SM420 is what came in the 3/4 & 1 ton models. Should be a bolt in, except for the closed driveshaft.
While the 3.90 gear is a little low for highway use, there's not much choice unless swap for a late model differential. That can get you 3.73 and 3.42 gears.
Fred
52 3600
69 C-10
| | |
|
|
