250 inline 6 trans swap

[70 C20 in progress]

I have a Muncie 21 4 speed and I want better fuel economy/lower rpm during highway speeds I heard a t5 will bolt right up but I didn't know if that was my only manual transmission option if a 5 died is the best I can do I will but this is my daily driver and I plan on keeping it for the next 50 years of it's life 1970 C20

[zicc1835]

Originally Posted by 70 C20 in progress

I have a Muncie 21 4 speed and I want better fuel economy/lower rpm during highway speeds I heard a t5 will bolt right up but I didn't know if that was my only manual transmission option if a 5 died is the best I can do I will but this is my daily driver and I plan on keeping it for the next 50 years of it's life 1970 C20

There is a few other things to do with the five depending on what it came out of speedo and some other slight issues i cant remember do a search in the box up top there are some threads about this conversion ill look for you also

[zicc1835]

here is one of those threads
http://67-72chevytrucks.com/vboard/s...d.php?t=173219
and yet another http://67-72chevytrucks.com/vboard/s...d.php?t=557179
Iwas going to do this many moons ago and bailed on it because of many of the reasons in these threads good luck if you decide to go forward it can be done and has been done

[70 C20 in progress]

You were going to switch to a 5 speed? What stopped you?

[70 C20 in progress]

Btw those are talking about a 350 I got a 250 inline in my truck

[BCOWANWHEELS]

it wont hold up

[67 twins]

Originally Posted by BCOWANWHEELS

it wont hold up

Behind a 250? Sure it will no problem

[Mike C]

Get a donor trans from a 4.3 should be great on your 4.1. You will be thrilled with how much better it drives. An M21 is a terrible choice for an L6 powered truck so the 5 speed will do everything better. The M21 with it’s 2.54 first gear is completely lacking compared to the 3:1 or so the 3 speed would have had.

[LockDoc]

Originally Posted by 67 twins

Behind a 250? Sure it will no problem

^ I agree. I have an S10 five speed in my Green '67 with a 250 I6 and it works great, and made it a lot more enjoyable to drive.

LockDoc

[maverickmk]

Originally Posted by LockDoc

^ I agree. I have an S10 five speed in my Green '67 with a 250 I6 and it works great, and made it a lot more enjoyable to drive.

LockDoc

Did you use the hydraulic clutch or were you able to keep the mechanical set up?

[LockDoc]

Originally Posted by maverickmk

Did you use the hydraulic clutch or were you able to keep the mechanical set up?

I kept the mechanical. Unfortunately I didn't do a write up on it.

I purchased the spacer plate and used the '85 Astro van 11" clutch disk. I didn't have to use the adapter ring in the bell housing locator hole, it was the right size for the S-10 front bearing retainer.

Here is where the shifter is in relation to the bench seat. I bent the shift lever straight up from where the sharp bend was and it worked pretty good. It isn't as close to the dash as it looks. The shifter on it now is off of a full size pickup 5 speed and it is too big to screw on the shaft and too long. I just slid it down over the shift lever so I could test drive it.

The yellow circle shows where the original shifter hole was and the new hole is about 8-1/4" back. The shift tower on some of the 5 speeds is a lot farther back.

LockDoc

[BlouDon]

Originally Posted by 70 C20 in progress

I want better fuel economy/lower rpm during highway speedsC20

So did I - for my '59 Apache. I decided to go with a 3.15 ratio rear axle abundantly available around here. Works fantastic. Wont be good for heavy towing to loads, but my 59 will never again do that anyway.

http://67-72chevytrucks.com/vboard/s...2&postcount=14