I finally got it. Tried the washers but then the seat wouldn't slide back because the slider would hit the bolt. Got the cordless impact out and it went in like a charm. Then took the ratchet to see if it stripped and it didn't budge so we are good. Shouldnt ever need to come out again unless I sell it, buy I have a feeling that if I sell it the 200 lb box and subs are going with it. Lol was a pain to get the damn thing in.