do you meen what water neck housing or what thermostat ??,the earlier mopars use a bigger t stat then modern,,the modern use same size as a gm,,
its the spacing on the t stat housing that some times is diferent,,mopar has a t neck,that has a 90 degree curve in it,,,but it is for the bigger t stat,,i use a GM, t stat housing on my 340 it faces out not up like a mopar,,but it uses the smaller more modern t stat,,and the gm HOUSING HAS THE MOPAR BOLT PATTERN,, but i had the housing machined to accept the t stat lke a mopar housing,, a slant 6 housings bolt pattern is different then a 318/340,,and im sure your magnum is the same bolt pattern as a v8..measure your bolt pattern on ur engine,, i have a slant 6 housing,,you can have cheap if it will work for you,,,let me know il get pics if you need,,
