I don't believe the exhaust manifold crack is from off roading. It's a common problem with TJ's. I had a 2002 TJ that I bought new, and the exhaust manifold cracked on it. I hadn't taken it off roading in about 2 years at that time. I bet you'll meet a lot of TJ owners who's exhaust manifold cracked at some point.
Don't use 4x4 on paved roads. It was meant for offroad only or adverse weather conditions. When you're in 4x4 both front wheels are being driven and if you turn, the outside wheel needs to go faster than the inside wheel and it stresses the tires and the whole 4x4 assembly which may result in a busted transfer case very soon.
Surprised that cracking manifold is still an issue. Two pieces manifolds were used to address the problem in 1993. Too compliant trans mount seems to be responsible. The I6 block flex may also be the cause. After market manifold offer an answer.
I have about 85000km on my 2004 Jeep TJ. Only problem is the fan motor switch (on the inside) my lowest setting does not work, medium and medium high and high works fine. I had the same problem on my jeep liberty..
Not to be TOO picky here... But I will recommend you folks go check out jeepsunlimited - it's a forum for Jeeps and pretty much everybody here would benefit. To the person who said the "transfer case" would be damaged? No, it would not... The transfer case has NOTHING to do with the wheels turning in different ratio side-to-side. What you would do is break an AXLE. The transfer case has a single-shaft going into it... and to the person who posting about smoking all tires going uphill on dry pavement? Don't anybody believe that nonsense. It would take a lot more than the listed mods to achieve anywhere CLOSE to that. Like I say - pop in on any JEEP forum if you want to get real facts and get questions answered. And any 04 Jeep with just a bent up fender and door would NOT have been totalled. Perhaps this is just a "funny forum" and I missed the humor somewhere along the way.
The person who said he can smoke all 4 tires going uphill, I don't believe it. I don't know if you had lockers, but even if you did, getting all 4 tires to light up would be damn near impossible without something breaking, especially if your Jeep has the infamous Dana 35 rear axle.
Besides, 4x4 on a Jeep Wrangler is a part-time 4wd system, meaning that exactly 50% of the power is being sent to the front wheels and exactly 50% to the rear wheels. This is not the optimal solution for driving on dry paved roads, but does offer great traction off-road. An AWD system, such as that in Audi Quattro, or Subarus offer the ability to drive on dry paved roads, as the power they send to the front and rear axles fluctuates to accommodate this better.
I saw a show on TV where they got a JK to light up all 4 40" tires. 'Course they had a 360hp hemi under the hood. Plus they said that there was some concern about breaking something in the drive-train. Nothing broke (44s front and rear) but they felt it was a delicate set-up. No kidding huh? 40s on one end and 360hp on the other can stress stuff.
"And any 04 Jeep with just a bent up fender and door would NOT have been totalled."
I used to rebuild wrecked vehicles. Usually you're right, but every once in a while I have found vehicles with very minor damage being sold with marked titles because they had been totaled. On a deal like that, I would make sure that ALL the fluids get changed because they may have been flooded. I really can't explain, otherwise, how that happens.