Eaton rear differential question

[G-749]

Hello all, 1970 C 20 Longhorn Eaton question , 89k showing on odometer, 1400+ since I bought truck, already towed 3800 lb double brake axle 28ft dove tail trailer empty , going to put 4200 lb Kubota
grapple n scrape blade on it . Put truck on jack stands , changed engine oil again, 20W 50
Valvoline , 3 qts Royal Purple 75 140 w synthetic in rear end , while on jack stands , I counted tire revolution to driveshaft revolutions , almost 5, prolly 4:57 . Here is question, rotating wheel on either side forward makes opposit wheel turn in reverse , when turning either wheel in Reverse , both wheels rotate in same direction , truck under power spins both wheels on pavement or gravel , SPID missing, 700R4 tranny works awesome under power and part throttle shifts , will change 3 gears before clearing intersection, looked thru search , about this , lots of info but nothing specific about this , pinion seal small leak , only got 2 qts out of it , no small tag on diff cover, diff has been opened, and RTV sealed by PO
Do I have a G 86 No Spin Axle based on what I have described? Inquiring mind wants to know what others think about this. Any and all thoughts , comments, input welcome .
Good luck on all your projects!!!

[kwmech]

complete drain and refill on an Eaton should take a gallon of fluid. Sounds like you have an open diff with 4.57s and a small block. Towing that heavy with a 700 is going to be your eventual downfall

[G-749]

Thanks,l did the search thing on here ,older threads but 3 qts seemed to be consensus from few posters
Anyway thanks for heads up to check fluid level, what came out was about 2 1/3 qts , I refilled them from drain pan, as for that particular tow operation, twice a year for hunt club work weekend, 120 miles
Round trip , 2 lane rds, gonna drive it,

[kwmech]

Double check and triple check in a few days. A lot of people don't factor in the oil filling up the wheel bearing hubs and the tubes. Then again I was thinking HO72 not an HO52. A 52 is not much larger than a Dana 60.

[connorm]

Originally Posted by kwmech

Double check and triple check in a few days. A lot of people don't factor in the oil filling up the wheel bearing hubs and the tubes. Then again I was thinking HO72 not an HO52. A 52 is not much larger than a Dana 60.

From what I understood about the Eaton HO52's and HO72's is that the only real difference is the pinion bearing, similar to the Ford 9 inch's bearings. There is also some Eaton HO110's in one tons and larger that are a completely different axle design

[R.O.B.]

Pretty sure last I looked up, our HO52's took GL-2 spec'd fluid. I don't think that Royal Purple is, nor backwards compatible. Please look into it

[MJN]

1971 service manual- GL-5 spec, fill until it runs out the filler hole.