I installed a set of Bilstein 4600s this past weekend. With Amazon back ordered, I ended up finding the fronts locally at Four Wheel parts. The old shocks looked to be original, Toyota marked KYBs in back and Tokicos in front. Odd that they were different manufacturers, but both were stamped with Toyota part numbers.
It’s possible the previous owner had them replaced at a dealer, but given the condition they were in I’ll believe they’re 20 years old. The Bilsteins went in smoothly, though as warned in an Amazon review the mounting ears for the front shock had to be bent out slightly to fit the shock. The ride is much better already, though the real payoff will be when the camper goes back on. Carrying that much weight on blown shocks was more than a little unsettling.