| |
Click on image for the lowdown. 
====
| | | Forums66 Topics128,195 Posts1,057,370 Members48,469 | | 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!
| | 
#37911 08/12/2003 6:22 PM | Joined: Apr 2003 Posts: 67 Shop Shark | | Shop Shark Joined: Apr 2003 Posts: 67 | Hi guys. I have a mint'58 GMC 2.5 ton flatdeck. The original 270 has bit the dust. I have a donor 350 small block on hand. Will this bolt up to the original Muncie 4-speed (Muncie SM420)?
The truck also has the original rear end. The 10 bolt single speed with a 5:43 ratio. Rear axle is 10 stud (#2367009).
To get better highway driveability and fuel economy, does anyone know of an 'easy' gear ratio swap? Would it be simpler to get a late model rear and swap drum to drum? Would a transmission change be a good option, such as an R700, or..?
Finally, my last question, does anyone know the easiest way to put power steering on this truck. What would be a good donor unit ?
Many Thanks,
Royzell in Shawnigan Lake B.C.
Royzell
| | |
#37912 08/21/2003 10:49 PM | Joined: Apr 2003 Posts: 140 Wrench Fetcher | | Wrench Fetcher Joined: Apr 2003 Posts: 140 | Lots of questions; I think I can only answer one of 'em, though. I'm pretty sure that the GMC and Chevy sixes all use the same bellhousing bolt pattern, and SBC is different. So you'll need an SBC bellhousing. But the 4-speed tranny will bolt up; they're all the same. You may want to consider one of the pressed-steel bellhousings from Summit or any speedshop, they can be drilled and welded as needed for "minor" adaptations.
The 58 was available with a V8, so you should be able to find motor mounts. As for the rear axle, heck, just let that ol' SBC spin up some! With good rods and pistons you can cruise at 4500 RPM.... ;-)
George | | |
#37913 08/23/2003 3:32 PM | Joined: Apr 2003 Posts: 67 Shop Shark | | Shop Shark Joined: Apr 2003 Posts: 67 | Thanks,
I may be able to find a used bellhousing to work here. I've since been told that the crossmember and mounts from a full-size Jimmy / Blazer will work here as well.
Like you say, i'll let the SBC rev a bit for a while.
Royzell
Royzell
| | |
#37914 08/23/2003 6:13 PM | Joined: Apr 2003 Posts: 140 Wrench Fetcher | | Wrench Fetcher Joined: Apr 2003 Posts: 140 | On the power-steering thing: there are folks who sell GM 605-series power steering boxes adapted to fit 50s cars; I wonder of one would fit a 50s truck? Or at least be adaptable with some bolt holes. I put one in a 56 chevy wagon....
Any old GM power steering pump will work; I got one from a 70s vintage car.
George | | |
|
|
| |
