Looking to get a clear hose that would snuggly connect to the nipple of the heater core on my 351. Can anyone Advise?

 

Well, it should be 5/8 heater hose.

 

I think thats right. I looked around and get all kinds of results. Im gonna back and forward flush it. Need a clear hose size that will fit it. Is the outlet and in the same size? Also is the right side out and left in?

 

Both are same size, I honestly don't know which side is in/out.

 

Its for sure 5/8s. Got a female coupler and hooked w another adaptor to my garden hose then took another part of the 5 8 hose and hooked to the other side to a bucket w two long clear hoses from Lowes A couple chunks came out but nothing huge or too nasty. Its a pretty easy task and im glad I did it bc the best does seem hotter for $11. I think I'm gonna get a new thermostat and see if that makes it hotter. Its decently hot now but nowhere near my mustang