OK, I have a 96 with 130k on it. Heater core is leaking. A/C system works fine so I assume no leak in the evap core but would you put a new evap core at the same time? Would hate for it to start leaking over the next year and have to do all of this again.
That little extra investment is gonna pay you back. Chances are your evap core could be the original unit, so it's not exactly new. If you don't replace it now, I bet it'll blow up within a few days after putting everything back together
Always do both at once. I'm working on mine right now. I was just going to replace my leaky evaporator core but once I found out how much of a PITA it is I went and got a heater core too. I don't plan on ever doing this job again myself. I'll just stick to playing with engines.
I had the reverse of the OP (evaporator was leaking, not the hater core), but had both done at the same time since it is such a pain and you are there any way. The heater core was original, but the evaporator....well I'm on number 3 (original factory unit, warranty unit after 3 years, and now this non-Mopar unit which I hope will last longer than the first two).
2000 Sport 4X4 4.0 inline six, AW-4 Automatic, stock
Original Owner 290,000 miles