It's worth nothing in a general 'market' figure (or to me), but it's worth whatever you are willing to pay and the owner is willing to sell it for... ;)
KBB and the others can place some sort of 'value' on it, but in the end, it's whatever someone is willing to pay..
155,000 miles should be nothing for such a highly rated rig back in the day it came out (Consumer Reports, for example)..
My 16 year old F150 with over 247,000 miles on it rated 'very poor' according to CR, yet the old thing runs like a champ and I have no desire to sell it anytime soon... :) Besides, it's got about the same 'value' as that Tundra has to the general market too... Which is nothing... ;)
Personally, it's not the kind of rig I would be looking for, so I wouldn't pay anything for it.. ;)
Can it tow my #5000 TT?? I'm sure it can.. But, I'll take my F150.. :)
Good luck!
Mitch