Did my 94 a couple of years ago it was fun!
The J Chanel will go with the help of a rubber hammer,
I used a router with a carbide straight bit to finish sizing everything wd40/moveit kept the bit lubricated..go slow or it will fill the bit with aluminum.
The large panel on the top I held in place with 2" load type tye downs the ratchet type. I used 2, one on the front one on the back. it would have been easier with 3 the 3 in the middle. mine buckled a little the 3 one would have stopped this. Find the centre first on both parts, nail it down front and back then strapped it down tight and stapled it from there.
The side panel that fits the bottom has to go on first then the top one, then fit the 3rd one in the middle by trimming the flat side until it just fits. this is the one that adjusts in case you are off square a little. Not to tight thou because it moves quite a bit in the direct sun and will pull the staples if its to tight. Of course if not tight enough it will leak.
Generous use of good quality seam tape will insure that it never leaks again. The red tape is a good idea I used blue skin on almost everything..no leaks I have removed a side panel to check.
Pm me your phone # if you have a problem don;t know what I can do but i am willing to try,
Have fun!!