Just curious , we are taking an 81 chevy 5 lug rear end and putting it on a 66 , the 81 rear end is 1&1/2" wider on the 81 , has anybody tried to just cut down the axles themselves and slid them into the 66 rear end to achieve the 5 lug . But keep the earlier housing to gain that extra inch and a half for tire clearance ??
if both rear ends are 12 bolts you can swap the ring if both are 12 bolts you can swap gears-carrier & everything-from newer to old rearend.You need to use the old spiders on the axles and the new spider gears on the carrier, also you have to do some mixing at the pinion- been so long i cant remember exactly--maybe leave all the old stuff except for the crush sleeve.Its been about 15 yrs since I did it on a 63 c10 truck using a mid 70s rear for parts
If you are trying to achieve a 5 bolt rear wheel bolt pattern there are aftermarket axle available for your 66. That's what I did with my 63. (along with replacing all the bearings, the ring & pinion & adding limited slip).
I have a 66 chevy that I put a later model rear end in. Its bagged and lays frame so i just changed the offeset on the rims to clear the inner part of the bed.
I just did one of these, exactly as you asked. (like ten days ago) First, it's not 3/4" per side. The face to face width is 1.5" too wide, but the housing is only 7/8" wider. The brakes have different off-set due to wider drums (yet the backing plate is identical). You can narrow the axle housing 7/16ths per side, and it will exactly match the earlier model, then slide the earlier axle shafts right in. Use the narrow brakes from the early model. You have a narrow margin of error with c-clip axles, so be sure to measure three times before welding, and use an alignment jig specific to the job. The cheapest 5 lug conversion is the CPP axle set with drums. The cost to redrill stock axles from 5 to 6 lugs (or visa-versa) includes plugging and welding the holes, so it isn't as simple as it sounds.
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