Looks like I'm mistaken re the trim and paint location. Apparently '73 was the first year for this style of VIN tag.
Paint and trim are 492 and 430 resp. These will be listed in the factory parts book located on the Tom Collins site.
https://oljeep.com/edge_parts_man.html '62-73 J-series. The '73 TSM (available for purchase) tells you what the fields on the VIN plate are. However, nothing of interest there other than VIN and paint/trim codes.
VIN decoding is on page Ge-9 of the parts book. Paint codes on Ge-17.
492 is Jetset Blue metallic. Trim codes are given in group 29; 430 is there. Unfortunately each interior component is listed by the trim code, not vice-versa. If you have buff upholstery and a bench seat, you could infer that 430 is the code for that trim style.
I've no stake in the tailgate question, having never owned one of these wagons. Likely you should chat with other owners (like above) with personal experience.
No experience with replacement tanks for Wagoneers either. The original steel tanks (like you have) used a skid plate, which was
optional. The skid plates are around, or you could easily fab or have fabbed a duplicate.
Rocklaurence had this one for sale a while ago -
WagoneerSkidPlate (466 x 344).jpg
I have repaired a few Jeep gas tanks, both plastic and steel, and would go that way. Looking at your other post, your tank is dented but still functional. Do you have a spare tire behind the axle? I expect that your size of tire won't fit in that space. There are many options for an auxiliary tank behind the rear axle. Search and you'll find many threads and much discussion, both here and at IFSJA. $1300 seems like a lot for a replacement when you have what looks to be a serviceable original tank.
https://www.bing.com/search?q=site%3Afs ... k+Wagoneer
You do not have the required permissions to view the files attached to this post.