To do a front end alignment on a 1991 GMC Sierra K1500 4x4 requires some shims being knocked out, right? It's not just a standard front end alignment, right?

NO VIN told so>?
C2500 or K2500, Sierra is trim.
a PICKUP truck>?
Not a Suburban right?

most cars made have starter relay so the super expensive ignition switch does not burn up ST contacts.
and cars GAS have ignition module, only location changes (if a Distributor it's there) if not Dizzy it's in the ECU or on some cars fire wall to COP coils.
1991 C2500 guess a Pickup is it?
4.3L engine, sorry not doing all 5 engines and diesel
shows distributor and ICM and 1 coil.
and no relay starter see schem.



try here>?
https://eautorepair.net/Marketing/Default.asp

4.3L

These symptoms usually mean you have a failed main or big end bearing in the engine. If it gets more noticeable as the engine warms up, that type of failure is even more likely. If the knocking varies with revs it is more likely a big end. You may be able to get the sump off without pulling out the engine, and do an inspection.

I can't think what the brake warning light would have to do with all that.

FRONT END SHIMMY AND SHAKING COULD HAVE A TIRE OUT OF BALANCELOOSE OR WORN WHEEL BEARINGS, WORN OUT BALL JOINTS,WORN OUT TIE ROD ENDS, FRONT END NEED ALIGNMENT.BRAKE ROTOR WORN OUT OR WARPED, MANY THINGS WILL CAUSE FRONT END TO SHAKE SHIMMY.

your wheel bearings are gone

A bad ignition module can give you fits!!!! Replace it even if it doesnt fix it! You will be glad you did! Most likely that is the problem ,however!

Get the steering adjusted by a professional. You are talking about several different engineering diciplines coming together and they must be adjusted to complement each other. There is mechanical and hydraulic.

Thanks for your interest in FixYa.com

there should be a hole for a crank either next to the licence plate or between the bumper and the bed

Inner and outer ball joints?? If you mean tie rod ends u will need to set the toe in. Mesure the distance across the back of the tires and then across the front. The differance is ur toe in. Best take it to a wheel align shop and have it done properly it will save you a lot on tires.

sorry no diy, truck needs front end alignment the camber is way off thats why you are only wearing the inside of the tire

make sure piston is pushed all the way into caliper. if it is install without shims