[67FB400-4SPD]

Originally Posted by kenneth77

so what you say is that when the trans is assembled,i just take a brass hammer,and hit the countergear shaft thats sticking out at front of the case,and make it flush??

That is what I did and it worked perfect, but as you said above it was only sticking out about .035" or so in the front. If I remember correctly, I also had an issue with those 'crimped' washer tabs on each end of the shaft. One of the washers was being stubborn for me and kept rotating. I dabbed a nice cold chunk of bearing grease on it to keep it in place and that seemed to do the trick, otherwise that little bent tab on the washer would make it sit crooked when it was not sitting in that indention where it belongs. As far as the year you have...you should be able to research the year you have by the part numbers on each piece. The main case, tail housing, and cover should all have the part numbers on them...especially the main case in your situation.
If you let me know what those numbers are I can probably help you look it up when I get a chance. Hope this is helpful for ya...Jason.

[67FB400-4SPD]

Check these maincase numbers to match yours:

Maincase Gear Ratios Input Grooves Cluster Output
RPO Years Casting 1st 2nd 3rd 4th Spline (Input) Pin Spline
-----------------------------------------------------------------------
Muncie
M20 63-65 3851325 2.56 1.91 1.48 1.00 10 None 7/8-inch 27
M20 66-67 3885010 2.52 1.88 1.46 1.00 10 2 1-inch 27
M20 68-69 3925660 2.52 1.88 1.46 1.00 10 2 1-inch 27
M20 70 3925661 2.52 1.88 1.46 1.00 10 2 1-inch 27
M20 71-74 3925661 2.52 1.88 1.46 1.00 26 2 1-inch 32

M21 63-65 3851325 2.20 1.64 1.28 1.00 10 1 7/8-inch 27
M21 66-67 3885010 2.20 1.64 1.28 1.00 10 1 1-inch 27
M21 68-69 3925660 2.20 1.64 1.28 1.00 10 1 1-inch 27
M21 70 3925661 2.20 1.64 1.28 1.00 10 1 1-inch 27
M21 71-74 3925661 2.20 1.64 1.28 1.00 26 1 1-inch 32

[kenneth77]

main case is 3885010
tailhousing is gm 3846429
cover is gm 3884685
midplate is 3831752
front bearing retainer 3851326

top of main case is also stamped with the last vin digits

[67FB400-4SPD]

66 main case is 3885010
65 tailhousing is gm 3846429
66 cover is gm 3884685
?? midplate is 3831752
66 front bearing retainer 3851326

I would say that you are good as far as years go...the midplate part number shows as M-20 and M-21 for many years including 66.

[kenneth77]

the company i bought the parts from will send me a new shaft,and gaskets for free.
i also have to shim out the front bearing to get the same clearaence on the 3rd and
4th gear syncronizer rings.

however they stated that the lenght of the countergear i got was the same as they had in stock.i dont understand how it will fit as long as it is 9 29/32" and the case is
9 7/8"... maybe i just have to grind off some of the shaft,or make a "hole" in the bellhousing for the shaft

[67FB400-4SPD]

Good deal but don't grind into the bellhousing...if the shaft being replaced will be the same length I would suggest using a light sanding disc like a flap wheel or something to knock it down a bit. If you already slid it through all those little bearings in the countershaft that kind of sucks to do it all again but I guess that is the nature of the beast. You could order just that shaft from another supplier as the one I mentioned above. I have had absolutely no problems with any of their parts. Good luck to you...I am sure it will work out fine for you in the end. Jason