So I bought this a body 8.75 rearend for a steal and it came with everything but new axle bearings and seals. Now I’ve been told it’s a 4.88 year set but I’m sceptical about that. Guy told me over the phone it was a 489 case when in fact when I came to pick it up it was a 742. Thank god it wasn’t a 741. But I’m more in wondering what gears are in it since he didn’t even get the case number correct I don’t believe the gear ratio number he gave me either. It is a spool type that’s in it but here are the pictures of the part number on the gear it is a Richmond unit but I can’t cross reference the numbers at all. There is a section on the gear where someone scratched out something that might have been the gear ratio but this is all I have to go on. Thanks for the help In advance.
Can’t find any part number on the internet about my 8.75 742 case gears
- Thread starter dustyaman
- Start date
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Count the number of teeth on the pinion, count the number of teeth on the ring gear.
Divide the number from the ring gear by the number from the pinion.
Gear ratio check
Thank you appreciate the quick response. I’m new to rearend stuff.
d55dave
Well-Known Member
What is with the funky coupling on the input in picture #2?
Did you measure the housing to make sure it is in fact A body?
Did you measure the housing to make sure it is in fact A body?
d55dave
Well-Known Member
Yep I measured my 7.25 spring perches and the 8.75 spring perches they are dead on the money. And there is no grind and weld marks on the the tubes. Can’t believe I picked it all up for 400 bucks. Plus 2 440s 1 with 10.1 compression speed pro forged pistons and the other with a forged crank for another 500. With a set of 906 hp heads going to be fun going from a slant and 7.25 to this combo
Nice haul!
Since you haven't posted your ring and pinion gear tooth count yet, how about some guesses from the masses?
I'm guessing 5.13 (due to the thickness of the ring gear and the spool... IE racing)
Since you haven't posted your ring and pinion gear tooth count yet, how about some guesses from the masses?
I'm guessing 5.13 (due to the thickness of the ring gear and the spool... IE racing)
Yeah I’m at work right now so will post later lol!!
Another way to tell the ratio is to mark the pinion and ring. Rotate and count the turns on the pinion and see how many turns it takes to move the ring gear one full revolution. If its almost 5 turns of the pinion then 4.88 it is. Thats a steep gear judging on the ring gear thickness.
You can also use the same method with the rear in the car. Just mark the tire and count the turns.
You can also use the same method with the rear in the car. Just mark the tire and count the turns.
Soooo close.
Hey I give you the win. Your the only one that guessed lol
Na, give it to MoparMike1974 he nailed it even if he wasn't playing!
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