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#55943 02/02/2006 12:48 AM | Joined: Jun 2005 Posts: 50 Member | | Member Joined: Jun 2005 Posts: 50 | I would like to change out the rear so I can go over 40 mph. Would it be better to change the whole rear, and what one would fit in my 3600 with a 4 speed.Or, do I try again to find gears for a easy switch, and where do I find them? Thanks Paul
PJP
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#55944 02/02/2006 2:51 AM | Joined: Oct 2003 Posts: 363 Member | | Member Joined: Oct 2003 Posts: 363 | You can search the archives or click this link as I have it bookmarked.
http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=2;t=008307#000003
If you can find a big block automatic suburban, it may have 3.90s. Good luck.
Eatons are getting scarce around here as the mud truck guys found out they are bulletproof and have 4.10, 4.56 and 5.14s If I could just find one to swap my 5.14s for 4.10s | | |
#55945 02/02/2006 10:58 PM | Joined: Apr 2002 Posts: 1,571 Shop Shark | | Shop Shark Joined: Apr 2002 Posts: 1,571 | Check the pick-n-pulls. I got my 4.10 for $65 at one, they had two at the time. I think the other one went to the crusher, even though I posted several notices about it here.  Tom Meyer in Miami, OK probably has several if you can't get one locally. | | |
#55946 02/04/2006 5:27 AM | Joined: Jun 2000 Posts: 2,773 'Bolter | | 'Bolter Joined: Jun 2000 Posts: 2,773 | Swapping out the differential has some problems, but is a possibility. Biggest problem is that the newer differentials are wider. What you need to do is measure the distance between the brake drum faces. Also measure the distance between the fender wells, and the setback on your wheels. (Lay a straightedge across the back edge of the wheel and get the distance to the face that mates to the drum.)
Then you're off to the junkyard. The best swap is to a newer 14 bolt full floater. Just about any yard has them with 3.73 gears. Measure the differentials like you on your truck. Most are at least 3.5" wider, which will mean you need to find a pair of wheels with one or two inches more setback. Be sure what you choose will fit in your fender wells.
Next you will have to remove the spring and shock mounts, and weld either your mounts, or mounts from a donor on your newer housing.
All things considered, the pumpkin swap is far easier, but you're stuck with 4.10 gears, which are better than 4.57s.
Fred
52 3600
69 C-10
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#55947 02/04/2006 11:13 AM | Joined: Apr 2002 Posts: 1,571 Shop Shark | | Shop Shark Joined: Apr 2002 Posts: 1,571 | There are 3.90 gearsets for the Eaton out there, but you need to find a 1970 BB 3/4-ton truck - not the easiest trick. | | |
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