What oil is used in a 1996 Ford F450 truck 5 speed manual transmission? It looks red like automatic transmission fluid.

Based on Amsoil's Application Guide, it appears the manual transmission fluid is Mercon V ATF. Ford no longer makes or stocks plain Mercon ATF.

I would use either Mobil 1 Synthetic Multi-Vehicle ATF or Amsoil Universal Synthetic ATF, both of which are Mercon and Mercon V rated.