Vintage Thetford Conversion Question

[uwe]

I want to install a late model Thetford dump valve on my existing 1963 Overlander's black tank.
The bolt pattern is 6.5 in diagonal center to center, and 4 5/8in center to center if measured parallel.
I wonder if a modern Thetford valve would fit this pattern?
I have atached three pictures for clarification. One of the bottom of the tank, one of the bottom of the dum valve, and one of the top of the dump valve.
Andy at Inland says it might need a new flange on teh tank glassed in.
Did anyone do this recently?

[Flyincloud]

The newer valve wont fit , you will have to glass in a new flange after grinding the old out . Under the dump valve I found a genova 3 inch fitting with two 1 1/2 inlets covered with dust at local hardware store which takes both drains so works like old bronze dump valve without adding grey tank . I used 1 1/2 to 1 1/4 rubber adapters to connect to old pipes . I dont know if the genova fitting is still made , its the only one I`ve ever seen ,in local hardwares ,home depot etc.

I`m going under trailer today , I`ll get # of genova fitting for you
Chris 63 cloud