Vehicle won't start on park but on neutral

is probably the neutral safety switch

i agree with that.

Thank you so much I'll get it checked

Its also possible that the shifter linkage length just needs to be fine tuned. The transmission being changed points to that, as internal and external wear to trans parts effecting clearances at linkage bushings would seldom be exactly the same on any 2 transmissions-particularly true if the "new" one had been rebuilt or the old one replaced with a new trans.