I really don't think the needed mods are a deal killer, if somebody wanted to install these on a 150. The headliner will be out and the wings already off, so all it takes is punching four holes in the fuselage "rib" (to match the 152's fuel pickups) and installing a few pieces of the 152's plumbing. Certainly MUCH easier than modifying standard tanks in a 150's wing, plus you'll have less "unuseable" fuel... a plus in a tailwheel airplane. Since the 150 and 152 are on the same TCDS, this could be approved as an "upgrade".
