Sounds as if it could be operating as designed. It's a big jump from lo to direct, if it shifts upshifts any sooner it will have to downshift again with just a slight load or throttle increase. Every Power glide I've ever driven sounded like a s screaming jet right before WOT upshift.


BC
1960 Chevy C10 driver 261 T5 4.10 dana 44 power loc
1949 GMC 250 project in waiting
1960 C60 pasture art
Retired GM dealer tech. 1980 - 2022