They don't have to be for a first gen. Anything for a 95-2001 should bolt up to the front as well, even if it needs a little repositioning.
Most of the bull bars only come in a few sizes to fit small/midsize and fullsize trucks, so the only difference is the brackets that adapt them to the frame. Worst case is you have to drill some holes in the brackets, usually.
On the other hand, they aren't all that difficult to make. With a tubing bender and a welder, you make 4 bends, weld on mounting brackets, skid plate mounts, and light tabs, and you've got a bull bar.