hi ApacheFiend,
if it's the part i'm thinking of i would suspect it is a cast part,
does the broken surface look like tiny tiny crystals?
if it was me... and i'm no expert, i would decide like so
i would determine how much strength it needs where the fix is going
if it is light duty i would consider braising it then i don't destroy the part if it needs welding in the future if the braising can't hold up.
(but all the braising would need to be removed for future welding)
i've seen the whole cylinder head of a hit-and-miss engine braised together from the two former halves and it worked for years, if braising has enough surface it can be reasonably strong.
if i had to weld it, i would reach for a 1/16 or 3/32 nickel rod unless i knew for sure some cheaper rod could work.
put a lot of heat sinking metal behind you weld spot, consider preheating the part first to minimize warping, clamp the flat faces of the parts to flat things to keep it all square / parallel, don't unclamp it till it's cool.
how about going to your favorite wrecking yard and getting a replacement?
-s
