HELP! Will not shift into third in Overdrive

[Commodore Crap]

Tried the Jmod and failed. I did it on my 93 and it works fine. Tried the Marauder and no dice.
Will not shift into third. Fluid level is good. I took about 45 minutes to make sure that its good.
OD light flashes after maybe 5 minutes of driving.
I thought I messed up the separator plate and got a valvebody and plate from the junkyard. Installed it and same issues.
Scanner showed no codes.
I need to figure this out ASAP.
Thank you for all the help.

-ryan s.

(btw, the fan crapped out while getting the fluid level, so, I need one of those too. Suck)

[RacerX]

Fluid isn't too full is it? All checkballs were in their places?

[RF Overlord]

All checkballs were in their places?If you put another unmodified plate and VB in and still have the same issue, it does sounds like something simple like this was overlooked. It's easy to do, even multiple times in a row.

[RacerX]

Saw plate, missed VB.. ;)

[Commodore Crap]

I think I may have inadvertently cracked or broken that black plastic piece that has all the power and stuff running through it. I'm going to tow it home Saturday and then figure it out.
I have a spare 4R70W at home that I can take parts off and try and get this to work.

I thought I had messed up the plate, and I wanted it to run. So I went with the stock one just to drive it. Yeah, it's poo. But I'll let you know what happens. I must figure this out!
Thanks guys.

-ryan s.