Boyd's Tank in a '60 SWB Fleetside

[Too Slow '90]

My apologies for another tank thread but I've been researching for a few weeks and can't find much info on anyone who has installed a rear mount Boyd's tank in a short wheel base '60 Apache. If anyone has done one please feel free to pop in. I am ready to place the order but am unclear on what you have to remove to install it. Spare tire carrier only or it and the rear crossmember? Also does it matter (are there any installation issues) if the filler is offset or in the center? Both are top mount and I don't care which it is as long as I don't have to modify anything.

I know this one is specific to a Boyd's tank and I appreciate any help available. They are not cheap and I don't want to screw it up. Thanks in advance.