Folks, I can't find this in old posts. I count 10 bolts around the differential housing as I lay under my truck bed ('64 d100 1/2 ton shortbed with 3 speed) Is this the 8 3/4? I have found some surprisingly beefy parts in this truck merely, I guess, because it was a truck. Or is this the 7 something rear end?

Thanks in advance,
rock

If the back cover has no bolts on it and is one piece, it is an 8 3/4.

If it has a rear cover that is held on by 10 bolts, it is an 8 1/4.

The only pickups that the 7 1/4 made it under were the 4-cylinder Dakotas.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Not necessarily applicable to the OP's '64 truck. Remember, the 8-1/4" rear axle commonly identified by a 10-bolt cover wasn't introduced until 1969. There were lots of different rear axles prior to '66, many of which have 10-bolt covers. Best source of answer to this question is the FSM.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks much to both y'all!

Heartened by both, and finally getting smart enough to do some web work after Jeb's reply, I crawled back under with the mosquitoes and found a casting number on the part of the body holding the pinion gear "stem"..the rear end has a welded cover facing the real back of the truck and 10 bolts "inside" facing the cab. The casting number is 2070741 with a smaller 23 cast underneath that next to the old time (pre-pentastar) logo . AIn't vehicle work fun!
Dennis
rock

That there is an 8-3/4" rear axle. Congratulations.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

And you probably have the brake drums secured by a rather large nut - oh joy!!! Start looking for a suitable brake drum puller!

ok so a rearend with 8 bolts on the back is what????

A 7-1/4" with one cover bolt missing...?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

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what years were the 7 1/4 used??????????????????????

'60 (Valiant) to '98 (Dakota).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.