Hey Fellas, I'm trying to install a new spectra F30 tank into my 76.. the odd part is that it seems the straps don't line up with the reinforced part of the slots the carriage bolts go into... the Previous owner made this "adapter" piece that puts the carriage bolts in the right section and then the straps line up with the second set of bolts... If I get rid of this adapter... then the carriage bolts end up in a section of the slot that isn't reinforced and seem like they start to pull thru... not to mention I'm not sure these carriage bolts are the right size.. but maybe some pictures would help understand.
Looks like it has had the Mustang tank mod performed. Extending the slot for the carriage bolt is one of the changes needed to put in the Mustang tank.
That's not it, looked at mine and have no idea what is happening on yours. Here's the driver side of mine. And the passenger side that I modified for the Mustang tank.
I did the slot mod on my 73. I think 73 and earlier need it. don't know why your 75 would need it other than trying to put a non mav/comet tank in.