How do I figure out what I have?

[ChallengerHK]

I think so. As the suspension is compressed the shock pistons should compress as well, adding pressure to the system.

[Jamiez]

Definitely 4.5" back space.  Unless the guide I found online on how to measure it is wrong

[Jamiez]

Well the car is finally back off the jack stands and on it's suspension.  Air shocks still don't show much in the way of air pressure

Driver = 14.0 psi
Passenger = 14.5 psi

[HP2]

That's a pretty safe amount. If it does what you need, I wouldn't worry about it much.

[Jamiez]

Well there's very little clearance between the sidewall and the fender.  In fact there's a chunk missing out of the passenger tire that could be a result of a rub (car came like this).

It currently has P295/50R15 105S M+S in the rear and P235/60/R15 98S M+S in the front.

It looks like there are some P275/50R15 tire options out there.  Based on some quick web surfing that would result in a tire around 3/4" narrower?  Or am I way off ?

[Chryco Psycho]

how much room do you have between the tire & spring , possibly just a rim offset change could help ?
the way tires are rated 275/ 295 is the width & the height is the proportion of the width so 275 would be 1/2" narrower & the sidewall height is 50% of the width so you have it right , the 275 50 tire will be slightly narrower

[Jamiez]

I'll measure the space between the spring, but I'm going to guess the answer is "not much"
Edit:  I double checked, it's approximately 1"

It looks like one of the previous owners pretty much shoved the biggest tire possible in there without much concern for potential rub issues.

[Chryco Psycho]

so the tire you have should just fit with 1/2 between both the spring & body if you wheel offset is perfect

[Jamiez]

Can you change the offset on an existing wheel?

[ChallengerHK]

If it's a steel wheel, potentially yes, within limits. It's precision work, though, so you'd have to REALLY like those wheels to make it worthwhile. All in all, probably not worth it.

[Jamiez]

Well I finally decided to get back to this (after working on the engine for most of the summer).  I decided to go with replacing the shocks and see where that gets me. There's almost no pressure in them, and they've clearly leaked at one point.  Once I see how it sits and handles I'll be looking at the leaf springs.

Needed something to do in the winter anyhow

[Jamiez]

I actually found there is a part number stamped on the lowest leaf.  Mine reads 3643 595 which is the correct number for the 1974 JH23.  So they are stock height.