3/4T Tank install questions.

[swamp rat]

I bought my new fuel cell from Boyds on the last group buy, Nice looking tank but i have a couple questions.

Are the 3/4T frames taller than the 1/2T frames? When i clamped the tank to the bottom rail the top of the tank is about 1 1/4 below the top of the frame. i have seen a nimber of pic's where the tank is sitting flush with the top of the frame. The pic with the tape is a bad angle, the top of the filler is closer to 1 1/4 not 1 1/2.

It looks like when i do get the tank between the rails i can trim the flange a bit for clearance around the spring perch rivits then i could move the tank back another inch, but looking at the pic's do you think its nessasary clearance wise to the diff or is there enough clearance as it sits?