My 98 D1 receiver's hole was too low and did not line up with the holes in any of my ball inserts; I had to raise the top of the receiver hole with a big rat tail file until I could just barely get a pin to go through one of them. Anyone else had this problem?

I need to file a bit more out to make it an easier fit, but at least I can tow for now.

 

You sure the inside doesn't have debris in it or rust?
My receiver recovery shackle mount only fits one way, and not the other. But that's due to casting in the recovery mount, not the receiver. I've used a bunch of different tow hitches on different D1's and never had a problem.
What is that thing in your receiver, anyway?

 

I tried several inserts both ways including a hook and a three-way ball hitch and the receiver hole was too low on all of them; must just be the way mine was made.

The hitch in it now is a two piece deal that lets you raise the big vertical pin and slide the ball out part way, move it side to side, lower the trailer coupling, and then back up to push the slide in and the big pin spring down to hold it in place. It's heavy, but it saves a lot of getting out and in to move the truck when you can't see the ball from the driver's seat.

BTW, it is easier to line up my Grand Cherokee to a trailer because I can raise the tailgate and hike myself up in the seat to see the ball; I can't open the Disco's back door to see it, so this thing helps. Can't remember where I got it - I've had it for years.