The KJ your looking at has less than 43.5K for miles (70kms), really is pretty low for the year.
Not knowing what you can pick this up for (really cheap?) & how qualified your "expert" is and what tools and equipment is at their disposal makes kinda hard to venture a guess if this is a good purchase.
If this is a gasser it would have a 42RLE auto trans, if it is a CRD it would have the 545 auto trans. Check the trans fluid to see if it looks and / or smells burnt would be a great place to start. This could be minor, or more in depth. Are there any CEL's lit up? If so - seeing if you expert has a hand held scanner to read them would be a good step. Post up what codes there are - if any.
05 TJ RME 42RLE with some things
05 KJ CRD 545RFE, GDE Eco tune, Franky II, Al's 4.5 A-arms, JK Rubi Moabs, Silent Armors 245-70-17's, Spidertrax Adapters, Rola Basket, Fumoto Valve, Pinch welds pounded
FS or FT (2) JK Rubi 17" Moab Rims - really nice shape
Need JK Rear Spare tire bracket for project