Have a th350 that I had rebuilt, now when it shifts it goes from 2nd. to 3rd. almost instantly. What should I look at first?

I think the modulator is adjustable with an allen wrench. It will delay the shift.

Thanks, I'll give that a try. I did put on one of those red striped modulators, so I'll try backing it out a few turns.

Look at the governor first. Modulator has nothing to do with it.
If the governor and bore is not worn, check the 2-3 shift valvetrain in the valve body. Broken spring or stuck valve.

I pulled the governor and it looks slightly scored, but no major grooves. Checked the diameter with some digital calipers and got between .800 and .799 does it seem in spec?

I had also just replaced the 2.73 gears with 3.55's. not sure if that affects anything or not.

Thanks for the help! I ground the inner governor weights down quite a bit, and presto! Shifts great!