No, they're not interchangeable IMHO because the '93 uses a trans speed sensor in its tailshaft while the '98 doesn't. You'll create a whole new headache if you try and after the hassle of swapping it, you'll be sorry. The '98's also a better trans as the '93s were the first year and thus not as good generally. I've replaced several '93 trannys but in all fairness most, if not all never had trans fluid flushes either and failed with over 130K miles on them.
A reman OEM trans is about $1,500 from a dealer, plus labor (10 hours book time). The reman trans has a 1 yr warranty while used has no warranty, something to consider.