So, I bought a used Class IV hitch, with all the hardware, but do I have to drop the gas tank to get it mounted? There are 3 bolts on each side.
The two bolts closest to the rear bumper are easy, but the two bolts that are closer to the axle on each side are welded to a plate. Is this normal?

I can take pics if need be. To clarify, I have 2 loose bolts and 2 sets of a plate with threads welded to it (that fit in the other two holes) Make sense?

 

Here's a picture to help explain.

 

i'd take it to a welding place and have them weld it on. on all of our vehicals they are welded. it might like $50 to weld it but atleast u dont have to worry about 4 bolts being able to hold whatever your towing.

 

I can weld, but I don't really want to weld this on. I've have always bolted my hitches on and never had a problem with them holding up.

 

When I have had plates like that on previous vehicles, I had to fish them into the framerail with wire from the end. I believe it makes the connection stronger on the back two bolts. I would go to etrailer.com and lookup the installation instructions for a similar hitch to yours.

 

Well, I got it on....finally. The bolts on the right side of the vehicle were slid through the end of the chassis frame, and then I used an extending magnet rod to get it into proper position. The one on the driver's side might have been a little more difficult since there is a wire loom in that rail, but I realized that the previous owner left the same bolts in the rail (he had a hitch before, but I guess he couldn't get the bolts back out of the rail).
I used my magnet to flip them to the correct position, and they dropped in perfectly.
Jacked the hitch up and got to bolting it down. Ran to the store and bought a wiring kit that plugs into the wiring harness ($15) and I'm good to go.

Thanks for the link vester, it helped also.