Originally Posted by abouzahrr
...but i've been thinking about getting into a TJ to build a trail rig.
That you want to build a trail rig is cool. Based on that fact alone, there is one VERY key component you would be wise to hold out for... that is to make sure its rear axle is the optional and significantly stronger Dana 44 model.
A basic TJ came standard with a Dana 35 rear axle, you could optionally order the stronger Dana 44 as an upgrade for something like $255 back when that 1998 model was made. The Dana 35 is certainly adequate for mild wheeling/offroading but it is too weak to install a locker into and it's too weak for tires bigger than 33". Many have broken their Dana 35 axle shafts when they wheel a little too hard.
If that '98 TJ has the standard Dana 35, it'd cost no less than $1000 to replace it with a used Dana 44 configured for a Wrangler TJ... when you can find one that is because most Dana 44 axles are not configured to bolt into a TJ.
Most people who buy a Wrangler to offroad are VERY disappointed when they learn about the difference between the base Dana 35 and stronger Dana 44 axle only after they bought a used TJ and then discover it only has the Dana 35. I was one of those, I had to replace my Dana 35 with a Dana 44 back in '99 or so.
Don't bother asking the salesman for that Jeep what rear axle it has, he won't know and he won't care. But if you look at the Jeep and it happens to have the Dana 44, don't let the salesman know it has the better/stronger axle you want. He'll then hold his price firm since he will then know it's a "special" and very desirable/rare model.
The only way to know for sure is to look at the rear of the rear axle yourself. The base Dana 35 axle will have a perfectly oval differential cover with a black plastic snap-in lubricant fill hole plug. The stronger Dana 44 will have a threaded steel bolt plugging its more angular nearly stop-sign shaped differential cover.
I personally would pass on it if it has the base level Dana 35 rear axle since you want to build it as a trail rig.
This first pic shows the Dana 35, the next pic shows the far more desirable Dana 44.