want to change my diff. to a drop in unit. What years did chevy use this with 6 lugs? Thanks any help will be appreciated. right now it is the stock 58 3.90 10 bolt. Trying to keep truck stock as possible. With the exception of the motor and trans. Thanks for any help.
Well there is no drop in. There is a few that are real close but still have to be fabed. Sorry for the bad news. I looked myself to do the same thing. If you realy want to do some good I would strongly recomend a new 4 speed. Not the sm420. That would work well for you. Still maintain the big gears and power but have the overdrive. Good luck
Have you called any differential shops that build them seeing you are going to do a changeout . That way you could go to a unit out of a S10 or late madel sub. Your truck size means they will have to shorten the axles. I had a 78 chevy 1 ton built for my 48 1 ton with 342/1 gears and it is great. I used Hooper's Rear End Exchange Inc. 12201 Branford St. Sun Valley, CA 91352. 818 - 899 - 2515. Fax 818 - 897 - 0952. Differentials and rear end parts
Thanks guys for your replies. I did call a trans,diff rebuild place and got some good advice. When I get my act together I'll post some picture of my project.
changed out 59 diff for 70 swapped a 70 1/2 ton for my original 4:10. Modified backing plates and used original brake cables. Had the diff shop swap out the gears for3:43 POSI. The 70 bolted right in. Same spring width. Looks original except for the 12 bolt cover.
