2002 Jeep Liberty Limited 4wd

Hello, I am the proud owner (almost paid for) of a 2002 jeep liberty limited 4wd. It has been in the family (2 years with me and three with my mom) for 5 years now. It has 102,000 miles and about 7,000 of those miles are city (I only drive 6 miles a day to work and back) and the rest highway. My mom bought it from the original owner with 60,000 miles. It has been a low maintenance vehicle until recently. There are a couple of major issues and then three or four minor ones. I’ll start with the most pressing. About 8 months ago I replaced a flat tire with a mismatched size spare on the drive axle and drove for close to 6 weeks before I realized the tires were different sizes. I noticed the problem when driving in 4wd I started to notice a thunking sound and called a mechanic who told me to check the size of the tires. The spare was the original factory spare (235/70r16) and the rest of the tires were purchased used by my mother (245/65r16) I immediately replaced the spare and have continued to drive the car to work.
Since then there have been no real mechanical problems but the jeep is making funny noises. At first it seemed like my right front tie rod end was going out because of vibration at around 40 mph. I took it to a mechanic to have he tie rod end replaced and he said that the rear end is “going out”. Estimate is around $1600 to fix with used parts. Seems kinda high to me and i am wondering if I replace the rear end now, how long till I have to replace the front end and 4wd system? Will the rear end go out again if the front end goes out? Should I just start with new parts and rebuild he whole drivetrain now to save money later? I plan on keeping the jeep after it is paid off in May and am trying to look long-term. I figure if someone is going to rebuild it I should look for a specialist and what are the best replacement part brands? What price sounds reasonable? Thank you for your help and have a nice day.

Body? 4dr.

Does the Liberty have part-time 4wd (i.e. 2-HI, 4-HI, 4-LO, etc) or Full Time 4wd/AWD?
Full-Time 4wd is more sensitive to different tire sizes than part time.

Are you sure about the tire sizes? Tire Rack does not list any tires in the 245/65R16 size.

Ed B.

The first number was definitely 245 and they were 16" tires, I’m not sure about the other number and I don’t have the tires anymore. It is part-time four wheel drive. Thank you guys for the fast response.