I would like to find the valve body from any 66 400 engine with the Jetaway. The 66 service manual shows a different part number from the 330 trans. It also says there are more clutch plates in the 400 engines transmission. The clutch drum might be different too.

 

surely someone has changed out the ST300 (Jetaway)for a later three speed in their 66 442.

 

"surely someone has changed out the ST300 (Jetaway)for a later three speed in their 66 442"

Many have done this but that wasn't the question was it or did I miss something?

I swapped in a TH400 in place of my Jetaway but in a 66 that involves an aftermarket cross member as the TH400 was not an option in an A-body of that year. Many have also used TH350, 700R4, 200R4 etc.
Your thread was answered in another forum also. Seems no one makes a shift kit for the ST300 and the only mod I saw was on a Buick forum that involved opening up the primary feed hole from .090 to .125 for a firmer 1-2 shift. It also modified the governor weights and spring for a higher shift rpm.
I suspect these are the exact mods in the valve body and governor that GM did between the 400 and the 330. Unfortunately that doesn't address the deficiencies in the ST300 overall. Swapping it out is probably the best advice and idea.

 

Mainly what my comment was meant to be "does anybody have a 66 442 Jetaway they want to get rid of." It should have an NJ code on the servo cover. I'm not replacing anything. I'm using this trans in a street rod.

 

Okay, I realize this isn't particularly helpful, but I have to know: why would you want a Jetaway in your streetrod?

 

the code NJ for 65 442 would have the same recalibrated valve body for a more positive (harder) shift as the 66 442 Jetaway.

 

Purely economic. I have three of them. Not a hot rod car, just a cruiser.

 

I probably have two or three as well

Larry
lemoldsnut@aol.com