Rather than using an Extension # e88YR you might consider using a extended ball mount. We have a couple different lengths depending on how much distance you will need to your Dolly # DM9713093. The distances listed below are from the center of the hitch pin to the center of the hole for mounting a hitch ball.
15-3/4" Ball Mount # 80232
13" Ball Mount # C45270
11" Ball Mount # 40345
If you can provide me with some more information about the length you need and what size ball your dolly... view full answer...