88 2600 rad temp sensor

Hey guys, I've got a brand new radiator in the 2600 but I threw out the old rad and sensor I've looked up the radiator coolant temperature sensor part # TX18 but it won't fit.

The TX18 looks about 3/8 and the spot for it in the rad looks about 3/4 or so.....

Anyone have any idea?

Thanks.

can you get an adapter?? 3/4-3/8 fitting?? should work

I think the cross member notch is too shallow for an adapter.