Front end alignment question

In all the years I have been driving and throughout all of the many cars I have owned I have never had to have a front end alignment done. Now however, I do on my GTX but I am not familiar with how an alignment is actually done. My car currently has drum brakes on it but I plan on converting to disks at some point this summer. My question is, if I were to get an alignment done now as the car currently sits with the drum brakes, would I have to have it aligned again after doing the disk brake swap or would swapping out the brake assemblies have no bearing on the alignment?

Depends

If your disc kit uses the existing spindles, no additional alignment needed.

If you must replace the spindles you should have the alignment checked and have it adjusted as necessary.

it is always advisable to get alignment after replacing front end parts. remember, these cars were never even close when it came to production tolerances to start with, so if you swap spindles to the later, taller, style [F,M,J body] that will certainly alter your current settings.
if it were me, i would swap to your discs now, then get it aligned.
i don't know what you have decided on discs yet, but don't fall for the 73-76 A-body "is the only setup to use" story. the later, [3/8" taller] F,M,J body spindles WON'T cause alignment problems or overextend the upper ball joint, causing failure. if you are using an aftermarket kit, i would check the master cylinder size so you get the correct size for your intended use. our good DR. DIFF will set you up with an outstanding kit with the CORRECT size master, so if you have nothing now, contact him first !
just my experience and opinion from playing with this junk since 1959. your mileage may vary.......

alignments are usually "warrantied" for 6 months or a year.

firestone still offers a lifetime alignment.

I usually do this for all my cars and just have them checked once a year, or when I change out parts.

Getting an alignment on a vintage car it is often not easy to find a shop who can do it now.
Mechanics who have old school knowledge on 40 to 50 year old front ends are becoming scarce, and some alignment racks won’t even work with a vintage car.

As said find a guy who knows our cars & slip him a twenty to accomodate your requests. set the ride height to where you want it first ahead of time (some shops set it too low), to where your particular rims/tires look good to you in the front wheelwell. 1/2 tank of gas/tires aired up/your weight in barbells in the pass seat & have him pull em over to the drivers side after he drives it on the rack. Some alignment machines automatically compensate for drivers weight so talk to him about this (the twenty will help with this). As much positive caster as he can get & the offset bushings ahead of time are generally a good plan. a skosh (1/4 deg iirc) of neg camber & 1/16" toe in. When done my dart just floated down the road.

Wow that's the year I was born.

I thought I was old.

I just want to re-enforce what has already been said about finding a tech that is experienced with our Mopars. Most techs that say they are familiar with older cars are actually familiar with other brands of older cars and are used to dealing with shims rather that our adjustments which are free floating.

"older cars", meaning fox body rustangs ?

Might be easier to just buy the alignment tools and teach yourself than deal with a series of alignment places that can;t align worth beans.

Ran into that years ago, ended up going to the dealer to get my not yet 10 year old 87 Diplomat aligned and they failed too.

^^^ & there are some utube vids that will help you out. Once you set the ride height to where you want it & the cams turned for max caster then bring em out for camber then toe in & iirc toe in comes first

RR, toe is done last. caster, camber, then recheck caster. you will probably have to go back and forth with both until you get it as good as you can get it, as adjusting one will affect the other to some degree. add or adjust what you want to compensate for road crown. then do your toe, as toe doesn't affect either, but it's possible the others will affect toe, especially if caster is way off, because the lower balljoint will raise and lower the outer tierod connection. think bump steer.
that is the way i do it. your mileage may vary.

^^^ Noted, thank you!