correct, if the option page does not list it, then it had standard equipment.

That's correct! I wish they had checked off the M-22 4-speed trans instead of the air conditioning, but it was ordered in Del Rio, TX, so pretty hot in the summers. I'm not sure if they understood they would get the M-13 3-speed if they didn't select a transmission option??? Anyway, back to the OP's thread.

Dennis

HD Muncie 3spd was only avail as one ratio transmission as the standard equip trans in GT-37's & GTO's. Nearly all non AC 71 GT-37's, I have info on from the Survey, have 3.55 gearing.
Original AC equip 455 HO stick 233's like Dennis's HO GT-37 & my HO Coupe received 3.31's. Non AC received 3.55's.

When a GT-37 was equipped with factory AC & a 350 2bbl stick or 400 4bbl, the ratio in the original 10 bolt would be 3.23.

I believe the HD M-13 3-speed first gear ratio was 2.42, so better than the 2.20 first gear of an M-22 behind the 455HO engine.

Dennis

earlier comments were in connection to the HD Muncie 3spd in '71 Pontiac GT-37's & 400 GTO's, definitely a few different ratios in 3 spds of this era. The Coupe's original M22 & 3.31 XUK will see little time in the car.

The 69-74 Muncie three speed only had two ratios:
The ‘car’ or “B” ratio: 2.42/1.58/1.00
The ‘truck’ or “A” ratio: 3.03/1.75/1.00
I believe that GM’s designation for this transmission was an SM-330 - but depending on the model year, platform or model, it could have one of several RPO’s.
I have read on occasion that some full sized cars could get the “A” ratio, but to date I have not found anything to confirm this.

My observations suggest that “B” gear set transmissions always had a front bearing retainer with an OD suited for a car bell housing, and a tail shaft for a floor shifter, while “A” gear set transmissions always had a front bearing retainer with an OD suited for a truck bell housing, and a tail shaft with no provisions for a floor shifter.

Saginaw three speeds seem to be another case all together;
I gave up on trying to understand GM’s coding for them, and what gear sets they came with;
in part because I didn’t have a baseline to compare anything against…

3.55 gears might explain why, with the GT-37 I had in the late 70's, I could get no better than 15 mpg while commuting 100's of highway miles each week. Mine was a 350 2bbl non-ac 4 speed. Low gas mileage was one of the reasons I sold it as gas was skyrocketing to upwards of $.80/ga!!!! :)

if done properly, I doubt it would affect the value.

From the few first hand accounts I received from people who ran the Muncie three speed, they all suggested that it seemed to be gear perfectly, so I hope you're not looking for a dramatic increase in performance.

Everyone I have spoken to about this transmission cites it's bullet proof durability - and the only reason cited for swapping in a four speed, was for the "cool" factor.
(The guy who I got my '70 Muncie three speed, was quite clear in his assessment of making his car slower - his was a 350-2bbl Lemans of some sort.)

If you do go this route, you can swap over your chrome stick from the three speed shifter into an (OEM/correct) four speed shifter, and all you will be left to contend with is the reverse linkage.

Also, if you do go this route, there may be some people on this board who would be interested in getting that three speed transmission.

I changed to a B-W ST-10 4-speed with the 2.64 1st gear since my M-13 was worn out. It's in my thread somewhere...but I don't believe changing over to a 4-speed, especially an M-20 Muncie, would reduce the value at all. Just keep your original M-13. I just had to get the correct levers/rods to work with the trans which I got from Crash Enterprises. I reused the original shifter handle & 3-spd pattern ball, so you would never know there was a change. The original back-drive all worked too.

Dennis

Hope you have good luck on that.
Which plant was it built at ?
If it was Atlanta , they usually had one taped on the inside of a door panel

You might have a handful of minor options.
Carpet
Radio ? do you have an in-glass antenna in the windshield ?
SoftRay windshield ?
Recess wipers ?
super lucky would be a saf-t-track rear axle

These other guys will know for sure but seems like they all came with Rally2 wheels

Yep, Rally II wheels without the trim rings came with the GT-37 package.

Dennis