It's 5% different. Going from 3.7 to 3.889 you will feel slightly easier take offs and speedometer reading low by 2.5 MPH @ 50
As all '83 and up had 5 speeds or 3N71B automatic then the '85 must be an automatic.
Axles are swappable, the only pain will probably be disconnecting the parking brake cables from each axle. One is a slightly lighter gear but not enough to matter. I would also suggest doing the leaf spring bushings depending on how you plan to remove the axle. Unbolting the u-bolts or removing at the spring?
Hello all, recently purchased a cheap ($20) led harness and installed it. Very straight forward. Each plug is individually grounded. The only thing needed work was to rearrange the pins to the plug going to one of the outer most headlight harness plugs (to the truck harness plug). You also have to add power to the relays through a wire already included (already had a inline fuse installed). It was approximately a 15 minute install with the headlight already in the buckets.
SU manifold have water ports but all weber and Mukunis manifolds don't have water ports.
running sidedrasfts I prefer not having the water ports in the head to worry about springing a leak.
I used 1/4 pipe plugs on my first head.
If head has the water ports already from factory I think just the short tap will work. short tap as it bottoms inside the head