Rear End Conversion
 

I have a 66 GM p/u with step-sides and I would like to change it from a 6 bolt pattern rear end to a 5 bolt pattern rear end . Does anyone know what year GM or Chevy rear end I should use?

1/2 ton Chevy from '67-'72 will be 5 lug and bolt in

71 -up chevy/gmc 2wd had 5 on 5" bolt circle. These rears are 1-1/2" (3/4" per side) wider which helps to fill the wheel area better(and still leave room for decent tires/wheels)

the 71-72 chevy would be coil, and 73 up are leaf.

The 67-70 are still 6 lug.

The GMC were leafs, not coils like chevy.

I just left a reply on the other thread.

Rear End Conversion
 

Thanx , Matt167 Does the rear end have to come from a truck with step sides or will a short bed Chevy or GM work? Also would you happen to know what year power steering column will fit my 66?

the colum does not change, the steering box does.. lots of applications fit, well into the 80's Chevy will truck will fit..

step side or fleetside, dosn't matter as the frames are the same

Rear End Conversion
 

Thanx F&J So would I have any problems getting wide tires on the truck ?I don't want them to stick out past the step sides.

Rear End Conversion
 

Thanx Again Matt167

Bigrix66 -I merged your two threads.


later, mikey

No, they won't stick out at all. The original rear is quite narrow and the stock wheels & tires are sunk way in.

To the best of my memory any Chevy or GMC 1/2 ton 1971 and 1972 you can just swap the axles and brake drums into your rear end housing for a 5 on 5" lug pattern.For the front I like to change the whole front end from a 1973 to 1985. The whole cross member with power steering and disc brakes and 5 on 5" pattern bolts in with very little modification.We did it on my son in law's 65 Chevy.It worked out great.You can usually find a donor truck cheap.You can also use the new style engine mounts.

[QUOTE=speedydeedy]To the best of my memory any Chevy or GMC 1/2 ton 1971 and 1972 you can just swap the axles and brake drums into your rear end housing for a 5 on 5" lug pattern.QUOTE]



That's a little confusing perhaps;

The 64-69 Chevy pickup 1/2 ton rears are the "narrow" rears. The 5 lug axle shafts from a 1/2 ton 71-up won't fit 64-69 due to the fact that they are longer shafts.

The only 6 lug 1/2 ton rear that can be swapped to those later axles is the 1970 rear. !970 is when the axles got longer, but still had 6 lug. The next year(71) chevy went to discs, & 5-lugs.

Notice I refer to "chevys" when I list axle shaft swaps. GMC's used a different differential manufacturer (if I recall correctly), at least on the 4x4 1/2 tons.

So, I think it would be best to grab a chev 1/2 ton rear assembly from a later 70's & up. Those later 70s saw some better gear ratios for better highway use. I have a 2.76 1979 rear in my 63 suburban. Good old GM interchanges; I wanted to stay with the 6 lugs, so I just went with a 4x4 rear which still used 6. If I wanted the 5 lug, a 2wd would solve that. :D