Transmission Slip Yoke insertion depth
 

65 GTO drag car - TH400

My current Spicer slip yoke (casting #C3-3-319) looks to have an approximately 3" long shaft with approximately 1.5" outside the transmission with car at rest leaving 1.5" in the transmission.

I have seen a recommendation that there should be more like 3" in the trans and 0.75" - 1.0" of the shaft outside the transmission.

Do I need a slip yoke with a longer shaft?

How long is your tailshaft ? I was having a problem with a T400 out of a Olds station wagon. Rear section of the transmission is 9 1/2".
I ran the stock one that came with trans with adapter U joint for years with no issues. But I wanted to upgrade with the new engine's greater power. Tried to get a long one from Summit, they are long and all but the splines were not full length inside, so it stuck way out. Did not like it. Sent it back.
I tried the standard length ones and it just went past the rear bushing kinda like yours. Made a couple passes, not liking it.
What I did was call Inland Empire Driveline and sent them my factory one from the station wagon. They custom made one just like it with full splines but for 1350 U joint. Made from 4340.
Cost over 200$ but it was worth it.

Dragncar - Tailhousing looks to be 4" long

Get a new yoke. If you are racing I would not want a "casting". Forged or billet only.

Thanks Dragncar for the advice, especially since I just installed a higher stall converter. Will upgrade over the winter.

Any recommendations in terms of brand?

Strange