Here are some of the differences: FP has six head bolts, LA has four. FP has full sleeve bearing, LA has partial bearings. FP has booster port, LA does not. FP has needle assembly in venturi, LA has remote.

I only have one LA (.15 FP-S) but it seems to run well. I have several FP's that all run well.

Some were concerned about only four head bolts. Others were concerned about the partial bearing. I have not read of either being a problem.

For the RPM that most run for stunt, the booster port adds nothing. As a matter of fact, some engine reworkers would seal-off the booster port in the FP to help scavenging at stunt RPMs.

Some do not like the remote needle and replace it with the FP version. The remote needle runs well but is slower at responding to changes in needle (tweaking).

Oh yes, one more thing. Some replace the LA's plastic backplate with a metal one (FP).

Some also run the LA right out of the box. Most OS engines are good for plug-and-play.

To answer your question, before bidding on one on *bay I would ask the seller if there is anything wrong with it. Nothing like being able to fondle it and look it over at the LHS.

These are just opinions, I'm sure folks who run both a lot will chime in with some better answers.

George