The background info: I have a built up 64' Riviera with a fairly fresh stock ST-400. The trans was rebuilt by someone locally by the previous owner. Engine Spec: The engine is a built up fairly hot cammed 434 Nailhead with Headers/Mandrel bent 2.5" pipes, Doc Mod and ported intake, cleaned up heads, new valves, pistons, rods, etc and I have installed a 2000 RPM Hughes Converter which works awesome. Issues: Its leaked fluid since day 1 when parked from the pan rails. (resolved) The electric kick-down never worked, yes it has power and you can hear the solenoid click inside the trans. (resolved) Manual 1-2 Shifts are terrible. Slow and sliiiiiiiiiddddeee into 2nd under heavy throttle. The 64' shift quadrant and the "trick" and if you shift from L to D then back to L to manually hold 1st and shift and hold 2nd it takes about an hour to slide into 2nd gear. An automatic up shift from 1-2 if left in Drive is crisp and firm and fine for normal driving but could use improvement under 3/4 to Full power. Current State: After installing the converter it was time to sort out the rest of the BS with the trans. I fixed the bent trans pan rails that were causing the leaks. I pulled the valve body and realized they completely OMITTED the separator plate gaskets (Likely because they are damn hard to find for this one year only trans) and they cleaned it up using an 80-100 grit roto-disc which left it fairly scratched up. It is flat as is the valve body and case. So were relying completely on 57 year old cast iron, steel, aluminum to remain fully sealed...... Not a fan of this approach but... OK...(not really) The electric solenoid was a cheap **** replacement that was broken at the 2 of the 3 spot welds. The spring was laying in the bottom of the pan. Installed a new Borg Warner quality kick-down solenoid. Pulled the metal filter and pickup tube and found 2/3 of one O-ring hanging in the pump housing. Found the missing 1/3 laying in the back of the pan. They installed it using 2 O-rings and the lower one was damaged. The upper (closest to the pump) was in tact and prevented the pump from ingesting the bits of the torn ring. The Dilemma: I have built dozens of automatics of all flavors over the last 30+ years. So I have a very solid understanding of them. There are literally ZERO shift kits or documentation available for this ONE YEAR ONLY trans. The only thing in common with the >65 up units is the valve body bolt pattern and general location of the valves within the body. The case and valve body for this year are NOTHING like a 65-up. Thus cannot be interchanged. The Questions: Does anyone here have experience modifying the 64' ST-400 valve body, accumulators, separator plate etc. Does anyone have a Valve Body channel map indicating what fluid flow is taking place in each of the VB passages? (I have it for the >65 up) The 64' Buick manual shows the valve locations and exploded view of their assembly into the body and there are photos of each valves operation but they failed to tie all that together with an actual VB diagram. I attempted to change the 1-2 Accumulator Valve spring in the valve body (not the servos) by using a lighter & shorter spring on the OUTSIDE portion of the valve as on the 65-up this is supposed to firm up the 1-2 shift. (The 64 uses the adjustable type 1-2 Accumulator Valve) It did not work. The trans instead behaves as if the modulator vacuum line is missing. It shifts around 4000 RPM at light throttle into 2nd etc. So I am pulling the pan and going back to the stock spring tonight. The Goal?? Clean crisp shifts that execute quickly.