I need to replace my housing. Do I go stock, use one in stainless from Hardin Marine or get fancy and get the crossover with idler pulley and stainless thermostat housing. Just wondering who has used what and their opinions. I was told that with the Hardin one I just run water to the bottom of the headers and plug the upper holes. Thanks.

I would not do a crossover on a stock 500efi

How about this housing
https://www.hardin-marine.com/p-1256...t-housing.aspx

Or just stay stock?

Those are Sierra units. People have been having problems with these recently.

Here is one ,of a few, threads this year:
Mercruiser Thermostat housing

So, yeh, stay stock cooling system on these motors.

Thanks guys. Saved me some headaches. OEM it is.

Just ordered a Merc one from BAM. Thanks.