I should probably get it done at 18 years on the original. Is TB replacement beyond the average home mechanic's abilities? Although, I might be slightly below average.
Ummm... I would say it's not for beginners.
There are videos on youtube. Their quality is not great. The hardest thing is removing the bolt that holds the vibration damper (bottom pulley where the timing mark is) on and then torquing it upon reassembly.
BUT... it's vital that you understand what you are doing. This is not a parts change. You will need a working knowledge of the overhead-cam with cam follower engine. Without it, I seriously doubt you will prevail.
You will destroy your motor, instead.
The cam shafts rotate at half the speed of the crankshaft. Thus the large pulleys on the cams and the smaller one on the crank. The valves MUST NOT be open (protrude into the firing chamber) when the piston comes to the top of the bore! Two things can not occupy the same space at the same time...
I've been turning wrenches (professionally, in my younger years) for 50 years. I was
e x t r e m e l y careful, as I did this. I did it in three sessions, of about 4 hours each. The timing marks are very obvious and, with a aisian kit, there are yellow marks on the belt and a good instruction leaflet with drawings.
I would have to say no - do not attemp this particular job. On a risk versus reward basis. If you have ti change your engine - especially in a 4x4, the cost will dwarf what you might save by doing this yourself