Stock '04 TJ Unlimited springs on a '98 TJ Sport?

I have a sagging '98 Sport with a 4.0 eng. and Dana 35 rear. It has @
98K miles on it and the suspension is shot. I was planning on adding
3/4" to 1 3/4" spacers just to regain factory clearance, or better
since I run stock steel wheels with 31" tires. Other than frame rub at
full steering lock, I haven't had too much problem with fender
clearance (yet).
I'm a cheap *******. I don't have enough $$ to drop on a new lift. A
friend gave me the factory springs (only 5K miles on them) off his '04
Unlimited (which has a Dana 44 rear). Assuming that I can use the UL
springs if the mounts are identical on the 35 and 44 rear axle. I'm
thinking that since the unlimited is heavier that I might get a slight
lift over the original '98 ride height. Or it may just ride stiffer.
At worst, I get back to original ride height, plus spacers. Either way,
Can anyone tell me for certain if the Unlimited springs will fit?