$15k seems very high, but I'd think $6-10K
IDK, that range seems low to me, this rig is sort of a unicorn of sorts...
The combination of diesel, 4x4, manual trans, coupled with a pass through cab camper is pretty rare.
Yeah it's an 80's vintage rig, however it's also a Toyota, parts are easy to find and performing most of the repairs is well within DIY.
To amateurw7vp, also very sorry for your loss, your son sounded like a really cool guy.
I followed his posts in other sites/forums.