Tranny identification

[69DISASTER]

I just bought a 1972 C1500 and the tranny in it shifts hard. You almost have to double clutch it. It is definitely not a Muncie but it doesnt even look like a Saginaw. The tailshaft is almost non-existent on it. I mean it looks like the driveshaft practically goes directly into the back of the tranny. Have no pics or numbers yet. Any wild guesses? I looked at one site that had diagrams of Muncie, Saginaw, and Borg Warner's and mine looks nothing like them at all. The gear ratio in this tranny must be some high because at 60mph it feels like the engine is revving about 3500rpm.

[kwmech]

If it is still stock, it should have an SM465. It will have a pto cover on both sides of the trans

[69DISASTER]

I think it is. I know one thing for sure, that tranny seems like it was put in the truck for field driving not for the highway. At 60mph the truck seemed like it was revving about 3500rpm!!!

[69DISASTER]

I have a Goodwrench 350 crate engine with a 400 turbo. Would I have to search for different crossmember. If so do you know if the one out of my 69 chassis will fit

[Blazer1970]

The TH400 and SM465 are both 1:1 in high gear. To lower your rpms you need to go with a different rear end gear ratio, taller tires, or an overdrive tranny. Going to a TH400 from the 465 will actually raise your highway rpms a couple of hundred since there is always slip in the torque converter.

[69DISASTER]

So for now i guess a rear gear change is the answer, eh? Possibly 273"s or right around that ratio?

[69DISASTER]

I am not into the truck for racing, more for cruising and short weekend trips.

[Blazer1970]

3.07 is a good gear ratio for a ~28 inch tire w/o o/d.

[69DISASTER]

That's about what I was thinking. I have a 69 3/4 ton that has an automatic. What peices can I use from it to drop the automatic into my 72 1/2 ton. I figure the driveshafts are going to have to be changed for sure, what about the crossmember is it diferent from the 72, can I use it as well because I figure there has to be a difference between the auto and standard. This is new territory for me. I am more used to old chevelles and Montecarlos.

[Longhorn Man]

tranny
cross member
steering column for the shifter
assorted linkages from the bottom of the column to the trans
radiator
cooling lines
speedo cable
You MIGHT get away with just swapping out the front drive shaft. I pulled that one off once.
Then, as mentioned before, you'll still want a rear gear set to lower the RPMs at speed. I will second the comment on the 3.07 gears for cruising. The easy way is to just get a whole rear axle from drum to drum from another 71 - 72 C/10 (assuming yours is coil). Small block with automatic came standard with the 3.07, as did small block/4 speed (may be others too, but those two are off the top of my head)
This'll put your RPMs in the 2500-ish area.

[69DISASTER]

OK, got the radiator, crossmember, cooling lines, going with B+M floor shifter so no steering column swap, got the speedo cable so how bad is the driveshaft situation? Can I just change the front driveshaft? Mine is coil spring. Can I go with a newer coil spring rear end?

[Longhorn Man]

like I said, on the drive shaft, you might be able to just swap out the front one. Might not. if not, you'll be taking a trip to your drive shaft shop. If you can't find one, ask a shop who they use.
72 was the last year for coil spring rear axles in trucks. if you have welding skills, or a friend you trust with welding, then there's a whole bunch more rears you can use. I said 71/72 for bolt in ease.

[69DISASTER]

Sounds like you really have a handle on this stuff. What about swapping for a NV4500? I probably seem all over the map on this one but i am still in the learning stage with respect to these trucks. Do you know if it will bolt up to the existing bellhousing and will I still have driveshaft issues?

[Longhorn Man]

I can't tell you anything on that one, sorry.