904 valve body in 727 Transmission

Hello Folks,
Would it be possible to swap a 904 VB from a 1975 904 that was behind a my 225, INTO a 1968 727 that was behind a 440 Imperial?
This is in regards to my 1975 Scamp 225/904/7.25 to 383/727/8.75 swap.
I want to swap out the valve bodies - the '75 904 has three prong Neutral Safety Switch, my '68 727 has one prong.
Any problems with this? It seems the after market sells valve bodies as "904/727 valve body" same part number.
Thanks for any of your help - Much appreciated!
Harry

The park rod has to stay with the trans that it came in because they are a tad different between 904 to 727, not sure what you should do about the switch

Hey thanks for the reply.
Since the 727 is a '68 and my car and the 904 '75, if I swap the valve body, I'll be good to go with the correct neutral safety switch.

use the 727 park rod, and the 904 3 prong NSS with the 904 valvebody.
your 904 VB should also have the part throttle kick down module that the 68 VB may not have.

Besides the Park rod, the rear center bolt hole prevents interchange. The hole in the VB transfer plate is elongated and the hole in the steel separator plate is located at one end of the slot on the 727 and the opposite end on the 904.

A rat-tail file can be used to elongate the hole in the steel plate.

Thanks guys, I truly appreciate the great information. This 727 will be going behind my rebuilt 383 (my first engine rebuild).
It certainly seems very doable, even for someone like me who has never gone beyond trans pan and filter on a 727.
So far, keep park rod, add 904 valve body after elongating that hole in the plate. Thanks for the pics!!!

i forgot about that center bolt hole john.
thanks for clarifying that point.

Just a FYI, the configuration of the case around the accumulator changed in '71; a '75 VB will fit and function in a '68 case but the accumulator won't work as originally intended i.e. initial engagement of Drive will be more harsh.

sorry to hijack thread but, john kunkel, years ago you had a site that had soooo many tips for 904/727. does that site still exist? do you have a really thick book of tips to sell? i want one if you do?

Thank you for sharing your wealth of information on the 727 and 904!

I was just going to use this '68 727 with my 383 swap and started thinking about the N S switch issue. I thought I would get some info on the possibility of using the VB from my '75 904 (that I drove) with the added bonus of the partial kick down.

Filing a hole I can handle, but now I'm wondering if the harshness would be "too" harsh. I know it's hard to quantify "harsh".
Perhaps I should try to find a more suitable replacement VB?

There is so much misinformation around the neutral safety switch compatibility. I've read some people saying to just use the switch your wiring harness requires.

no worries.

That was the old Photobucket site, no longer accessible.

To use the 3-prong NSS with the '68 VB, simply swap the rooster combs. The '75 PTK module can be swapped onto the '68 VB and will function but the 40 mph limit function won't work.

So to be clear (bear with me) If I swap the rooster comb from the 75 904 into the 68 727, I will have reverse lights, and the car will not start in gear. What 40 mph limit function are you referring to? Thank you!

Yes, as long as you use the 3-prong NSS and wire it correctly. Along with the rooster comb you will need the end plate from the '75 (see pic below) to limit the travel. Elongate one screw hole.




The '71-later PTK module has a limit valve to prevent PTK above 40 mph, this valve is ineffective on earlier VB's so you may get PTK above 40 mph.

Here's a pic of my '75 904. The rooster comb and the end plate I need to remove.

Any tips?

Remove e clip on selector shaft,
Remove 10 7/16 bolts to remove valve body