Can anyone fill me in on whether the 1970 GS BB with a 3-spd manual has any problems to look out for? Is the transmission stout enough for the 455? I am looking into one the looks to be in really good condition but I have no familiarity with the 3-spd manual. Is there anything to look out for? Thank you
1970 GS 455s come with a fairly unique Muncie M13 3 speed. It’s a very stout gearbox that I would argue is considerably stronger than the upgrade Muncie 4 speed. The first thing I would look for is that the car actually HAS The correct transmission and hasn’t been swapped out for a lighter duty Saginaw 3 speed. Here’s an image of what the side cover should look like to identify. Steve weim55 Colorado
And one more thing: I have never attempted a rebuild on one of these but they are not very common and Parts could possibly be an issue. I have no experience if it shares internal components with another more common unit. Units that came from a car application are pretty rare, The same transmission was used without provision for tail shaft housing mounted shifter on Chevy trucks in 350-396 Applications 69 through 72. Those transmissions are much easier to find and have a deeper 3.00 first gear ratio versus the 2.42 first in the car Application. What to look for? Same as any other manual transmission, is it quiet, does it shift well up-and-down? And being picky, does it still retain the correct shifter for a Buick application as well as all the back drive components up to the steering column? Steve weim55 Colorado
They are definitely stronger than the Muncie 4 speed. all the shafts have double rows of needle bearings on each end, I have one from a 70 GTO. It will survive behind a 455
Looking at the 70 Chassis Manual seems to be the Muncie for the GS applications. Looking at the order form it looks like the Saginaw would have been used for the GS350 column shift and one would have to tick the HD 3-speed floor shift to get the Muncie. Anybody seen a column shift GS350? Looks like the production numbers may lump the column shift and the floor shift production together.
Thanks Ted. Interesting that a 3-spd. col. shift vs. Floor shift GS 350 would get a different trans. I guess they figured easier/cheaper to lump the GS in w/Skylark for that application & common parts for the floor shift 350/455 together. I've seen a breakdown somewhere that showed 49 (maybe 47) col. shift '70's. Never seen or heard of one. @Chris Lott has been hoping to find one.
Was the 3-spd the standard option transmission on the GS455 and all the others were upgrade options? Is that what made them so rare?
The 3 speed manual trans on the floor with no consolette was the standard no cost trans on a 1970 GS 455 or GS Stage 1. Super cool and very rare.
