transmission and gearing questions

[72c10lover16]

I have a 72 c-10 350 4b with an automatic trans behind it and i also just bought a 69 chevy c-10 straight 6 with a 4 speed. I was hoping to put the 4 speed in my 72 eventually but i was wondering how that would work out. some people have told me the gearing may be to low im not sure though.
Please let me know anything you know

[mrein3]

Both transmissions have the same final gear. 1:1. The only difference is that the auto will have some slip in the torque converter resulting in a slightly higher rpm on the highway when in high gear. That is why manuals get a bit better mileage than an auto with all other things on the truck equal.

The 4-speed may have a much lower 1st gear depending on the particular 4-speed you have.

[72c10lover16]

so the swap should work fine. does it matter what rear end i have in it.

[mrein3]

Originally Posted by 72c10lover16

so the swap should work fine. does it matter what rear end i have in it.

Switching from an auto to a straight stick in your truck, without changing rear end gears or tire size, will drop your highway RPMs slightly. The slight drop will come from not having a torque converter slipping like you have in your auto right now.

[72c10lover16]

so when i go to swap them everything will function properly?

[cdowns]

do lots of research on the swap such as changing crossmembers linkage etc// in my opinion a step backward

[Green Machine]

The 69 likely has a removable high hump floor pan over the transmission because of its height. Your 72 likely has the standard low hump that is part of the floor. If you swap the big 4 speed into the 72, you will have to cut out the floor pan and install the taller floor pan hump from the 69. You will need to cut a new shifter hole in the 69 pan because the V8 sits farther ahead than the 6 cylinder.

[72c10lover16]

ok thanks for all the help. i figured that i can switch the crossmember from the 69 and put it on the 72. i think i can do that anyways. i didnt know about the v8 sitting up farther but now i do. will i have to get a different bell housing to put the 4 speed on the v8? also would i be able to put my automatic from my 72 into the 69? so that i can resell the 69 and get my money back

[lilred67]

Originally Posted by 72c10lover16

ok thanks for all the help. i figured that i can switch the crossmember from the 69 and put it on the 72. i think i can do that anyways. i didnt know about the v8 sitting up farther but now i do. will i have to get a different bell housing to put the 4 speed on the v8? also would i be able to put my automatic from my 72 into the 69? so that i can resell the 69 and get my money back

you can use the same bellhousing. I THINK you can use the same fly wheel and clutch set up.maybe someone will know for sure!!

[72c10lover16]

is there anything else i need to know for this swap? what about driveshafts? i should be able to put the 69 one in my 72 right. thats after i switch the trannys.