Do both the old tank and the new one look the same physically? The tank should mount to the skid plate first and then the hole assembly will mount up into the frame. I put my tank in using a floor jack to lift it in place that helps quite a bit even if you have an extra set of hands.
1987 YJ, 258, Weber 32/36, HEI, Custom Sound bar, Hardtop/Sun-rider/bikini tops, 2" Lift, 1/2" Boomerangs, 1" Body & MM Lift. 32x11.5x15 Copper STT's on Black Rock 950 Lobos w/4" backspacing, Still need Front Bumper and Seats.
My build thread: [url]http://www.jeepforum.com/forum/f12/my-very-slow-87-yj-build-thread-1137667/[/url]