Trans' numbers and identification.. 3 spd-4spd

[sharkskinman]

Current 3 on the tree
What is it? What's ratio?

[sharkskinman]

3 speed just got

[sharkskinman]

Muncie? 4 speed I just got
What I've gathered with the numbers
38850101965 - 1967Patent Number, 1" Bore
38575841966 - 1970Passenger Speedo, 27 spline
1966- 1974 M20 Two (1)2.52-(2)1.88-(3)1.46-(4)1.00-(rvrs)3.11


I need as much info as I can for them
4 spd will work? On colomn w/separate reverse lever?

3 speed has top shifter with it
Can I use it on the 4 speed?


Picked up a rebuilt 72' 250 on the cheap
Currently have 3.73 rear
Believe I need a shortened drive shaft for 4spd?

Will 4spd work well with engine and rear end??

[DKfromIA]

I'm finding that the Trans with casting 3830210 is a Muncie SM318. Ratios as follows:

1st- 2:94 to 1
2nd- 1:68 to 1
3rd- 1 to 1
Rev.- 3:14 to 1

This info is not from my first hand knowledge, however. Hope it helps.

[frankslagoon]

Originally Posted by DKfromIA

I'm finding that the Trans with casting 3830210 is a Muncie SM318. Ratios as follows:

1st- 2:94 to 1
2nd- 1:68 to 1
3rd- 1 to 1
Rev.- 3:14 to 1

This info is not from my first hand knowledge, however. Hope it helps.

The second 3 speed is a sag' but it's kinda special cause it has a tailshaft housing with bolt holes for a shifter. the 318 Muncie doesn't have a sycro first gear pretty light duty also. the gears in both the 3 speeds are pretty close to the same. the column linkage will be different between the two 3 speeds. but the guys are maken them work. I love the 4 speeds in the trks. I had one behind a L6 and it worked fine. If you have linkage for the sag. that's gona be the cheapest way to go. and ya won't end up with some goofy reverse shifter rod . which will be a nightmare.

[DKfromIA]

http://67-72chevytrucks.com/vboard/s...Sm318+m20+swap

This thread has info on swapping an SM318 with an M20. I don't think it answers all of your questions, but it's a start (if the transmissions are correctly identified as SM318 and M20).

[sharkskinman]

So have to get a shortened drive shaft( or shorten mine)
Or is there a truck that has the correct length driveshaft?

Top shifters are specific tospecific 4 speeds?
Got a shifter n such for the 3 speed but sure it won't work
Are 3 speed shifters all same? Will post pics of shifter tomorrow

I'm guessing the m20 is syncro 1st

Any more specific details or links will help