Super stoked here, as I believe I've found some 4.10s for my 3600. I just wanted to confirm that both of the '68-'72 HO52s and HO72s are compatible with my stock axle? I've found a guy with one marked RAJ G308 and I believe it's this one from previous posts.
The �72 series C-20 RAH, RAJ, RJA, RJB, RKK, RKL, RKS, RKT, RJP, RJS, RKB, RKC, was an Eaton HO-52
I'm just confused about the difference between the 52/72 models and really hope that I've found 'The Holy Grail'
Yes your axles will work fine, check out the article above in the Tech Tips section. Good luck and watch that speeding with the new gears.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
I have 32-33” tall tires and 4.10 gears and still take off in second more often than not. The 4.10 is a great swap, but the advantage is on the top end speed, not low end gear choices.
Either the 52 or 72 with the 4.10 is a good donor.
To complete the 4.10 upgrade a T5 transmission with a .72 or so 5th gear brings our trucks into modern gearing territory. That said if you truly work your truck and have a stock engine, then the T5 may be a bit much. I do find myself missing the original SM420 first gear creep mode when in the hay field loading square bales or creeping down a particularly rough woods road. I don't miss it enough to go back to the 420 that's still in a corner of the shop however. It does give stump pulling torque but it really is nice to cruse at 60 mph with a quite and happy engine.
Looks like it could be what you need. Big tell is the round gasket face (where the differential meets the housing) and 10 bolt holes. The images below show the 4.57's from my 3600. You're looking for a set of 4.10s that look like this, just different number of teeth on the ring gear and pinion. Now, if it has a locker the internals won't look the same but the housing will.
It sure looks like the right one to me. Can you take a look at the number stamped on the back side of the ring gear and maybe post it ? You should have 41 teeth on the ring gear and 10 on the pinion.
Ron - - Dusty53 1954 Chevy 3604 In the Gallery Forum "You can't dance with the Devil and then wonder why you're still in Hell." "They will forget what you've said, and they will forget what you have done but they will never forget the way you made them feel."
I bought a pinion seal when I swapped gears. After running the new gears the pinion wasn’t leaking, so I haven’t replaced it.
The pinion nut is a special one, unusual thread I think. Mine is rusty, so without a spare nut on hand I haven’t been excited about pinion seal replacement either.
If yours doesn’t leak might also want to leave well enough alone.
Another vote for leaving well enough alone. My experience is it's much easier to change the seal with the carrier in the housing, the support from being bolted up helps with breaking the pinion nut loose.
With the above said when I had my new to me, used 4.10s ready to install it was an easy decision to bolt it up and try it. If it leaked, then change the seal. Good news is no leaks with over 2,000 miles so far.
