I recently acquired a 1959 1/2 ton shortbed fleetside w/4 speed manual.
The rear axle appears to be non-original. I'm guessing it might be from a
71 3/4 ton, but I really have no idea. At 60 miles per hour the engine
(350 chevy) is really spinning, so I either want to change the transmission
or rear end. The axle bears the following information when viewed from the
driveshaft side:
B or 3 896389 driveshaft GM71
N
Now for the questions:
1) Any idea what this is from or what the axle ratio would be? How would I
find out?
2) What are the internal ratios of the original 4 speed transmission?
3) What more modern transmission would be a good replacement? If I
convert, I'd like to retain a "granny" gear and get an overdrive gear. So,
I guess I'm really looking for a 5-speed truck tranny that will fit without
a lot of modifications. What are my options?
4) If I wanted to change the rear, I'm guessing the easiest thing to do
would be to get the entire axle assembly, drum to drum. That way, I could
also get a 5 lug pattern. What axle would give me the same rear width and
bolt right up? I'd like to find a posi unit, presumably in the 3.07 to
3.38 range.
Keep in mind I will probably only switch either the transmission or the
gears, not both.
Thanks.
Jason
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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