I know it's 3 years too late for OP, but I found the transfer switch in my '97 Pace Arrow Vision and maybe someone will find it useful in future.
It's INSIDE the distribution box under the fridge. If you remove the cover of the AC (left) side you'll see a circuit schematic that shows the transfer switch being in the box. It's BEHIND the 12VDC fuse block at the right.
In the '97 the circuit breakers are in vertical pairs. I bet the change to your '98 vertical stack of horizontal breakers is designed to make room and you'll find it on the left, INSIDE!
I didn't dig it out, but the front sheet metal is spot-welded together so you'll have to go in through the back of the box if you need to repair something. There are a few sets of wires, labeled "Gen set" and "Shore" connected using wirenuts. You could probably put a voltmeter probe into the back to do troubleshooting
Thanks to all of the contributors above! I totally thought it was the gold box and didn't notice the 13A rating.
