Well I have no third gear. Once again! The frictions are new. So it must be the sprag?
The car runs and drives when in "D", it just won't shift into those gears? Try the input turbine sensor, on top of the trans (reachable through the side cover).
2003 GT Limited Edition 199k - The $600 winter beater. 2004 Buick LeSabre 172k - Top Swapped, 3.5 pulley, 1.9 rockers, SLP headers... still slow... MAKE AMERICA FAST AGAIN!