T-400 trans question
I have a th400 in a 1969 firebird, 3.55 rear, 25" tire. tach shows 3500rpm at 55mph. calculator says I should be at 2700rpm. trans and TQ conv are new 10/2010. 1800 stall. Any idea what might be wrong? tach and speedo are correct. thanks. also anyone do a 200r4 swap for a 69 firebird?