Hello all and thanks for all the info on the valve.I have solved the heater valve issue. (aftermarket product) What we need for our SC`s is a vacuum controlled,normally closed,vacuum opens 5/8 hose valve.What worked for me was a ford et4z18495a witch also is motor-craft yg256/yg264.(found on eBay for $23) What will also work is four seasons 74604 & 74614.I tried the four seasons 74858 witch is the same as the motor-craft yg368 with the doorman 47062 5/8 elbow.That valve is opposite, its open normally and closes by vacuum.Heat in summer so you have to plug the vacuum line in summer and reconnect in winter.(I live in NYC.) I Just left the old bracket on with the plug connected and all is well.I took off the old vacuum diaphragm also.I had to use the 5/8 elbow too. You also will have to buy a smaller vacuum line for the valve the stock Lexus was a little to big and couldn't create enough vacuum.I am going to try and attach a picture.My car is a 93 SC300.Original family owned.

 

Would seem that Murray 74850 from O'reilly's works. It looks practically identical to the old four seasons valves so it might just be the same exact thing with a different part number. Apparently it's for corollas. Requires shaving off a bit of excess plastic and reusing existing actuator arm but it spins in the correct direction and is only 60 bucks. Can do a writeup if anyone's interested.

 

What seems to be missing in this discussion is the diameter of the inlet/outlet tubes.
It seems the OEM diameter is 5/8 inches, whereas the 74850 has a diameter of 3/4.

 

Sounds about right. The hose fit on the valve with some wiggling and forcing. it took some silicone lubricant and a bigger clamp, but hey, it works.

 

Update: replacement valve's leaking. Has been dripping for a few weeks but now I'm smelling burning coolant when I step out of the car. Thanks china. Gonna order another and hope for better luck, if all else fails I'm going the ford valve route or something.