67 M-21 bolt head markings

[Lawrence S.]

Can someone tell me the correct headmarkings for the bolts that fasten the tailshaft to the main body of the transmission? I noticed there are two different sizes of bolts.

Thanks,

[Rich P.]

Re: 67 M-21 bolt head markings

Can someone tell me the correct headmarkings for the bolts that fasten the tailshaft to the main body of the transmission? I noticed there are two different sizes of bolts.

Thanks,

The 3 top bolts are grade 2 3/8-16 thread. Headmarkings---SBC, RBW, G, RSC and others.

Bottom 3 all are 7/16-14 thread the outer 2 are grade 2 same headmarkings as above center bolt is grade 5 headmarkings---TR, L5, M and many others.

Rich

[Lawrence S.]

Re: 67 M-21 bolt head markings

Thank you Rich

[Tom P.]

Re: 67 M-21 bolt head markings

I've been rebuilding Muncies and T-10s for 40+yrs, and about 20yrs ago I finally gave up on trying to determine if the bolts that were in the trannys when I received them were the originals or if they had been replaced at one time.
Between the 6 bolts on a Muncie tail housing, I've seen multiple head logos on all 6, and different ones from one tranny to the next.
And, frequently, for customers who want a solid, well built tranny and could care less about bolt head logos, I frequently replace bolts with new ones. Also, on the 4 front bearing retainer bolts, I often replace the originals with longer bolts. I can't count the number of Muncie cases where I have seen one or more of the front threads pulled out------------BECAUSE OF THE SHORT FACTORY BOLTS. I've had to Helicoil LOTS of them.

[Rich P.]

Re: 67 M-21 bolt head markings

I took these pictures yesterday just before I saw this thread....The RSC bolts are for the front bearing retainer and are 3/8-16 thread with a small 1/2" hex to clear the bellhousing opening. The SBC, TR and RBW bolts are for the lower tail shaft, the 3 SBC bolts are for the upper tail shaft, the 7 SB bolts are for the side cover and the M bolt is for he speedo cable/gear retainer.

[Rich P.]

Re: 67 M-21 bolt head markings

2 more pics

[Tom P.]

Re: 67 M-21 bolt head markings

I took these pictures yesterday just before I saw this thread....The RSC bolts are for the front bearing retainer and are 3/8-16 thread with a small 1/2" hex to clear the bellhousing opening. The SBC, TR and RBW bolts are for the lower tail shaft, the 3 SBC bolts are for the upper tail shaft, the 7 SB bolts are for the side cover and the M bolt is for he speedo cable/gear retainer.

There are NO bolt holes in ANY shaft of a Muncie, such as a tail shaft.
BUUUUUUUUUUUUUUUUUUUT, there are bolt holes in the tail HOUSING, or, extension housing, if you prefer!

[Lawrence S.]

Re: 67 M-21 bolt head markings

I put the transmission back in the car today and did not sweat the bolt head markings. But after looking at these pictures most of the bolts match Rich's pictures. I do have a few bolts with just a "G" on the head. I dont recall this style bolt as being original? Anyone else?

[Rich P.]

Re: 67 M-21 bolt head markings

YEP G is correct for the tail shaft HOUSING (see Tom you can teach an old dog new tricks)

Rich

[Lawrence S.]

Re: 67 M-21 bolt head markings

Good deal.