300D coolant hose size
 

Getting ready to convert my 83 300D to run on SVO (grease) shortly. For the coolant supply, I will be tee-ing into the hose coming out of the block near the oil filter housing. What is the size of that hose barb on the block? For the return, I will be tee-ing into the hose between the water pump and the mono valve. What is the size of that hose? I assume it's the same size as the supply.

I used 3/4 inch Ts for both

Yep that size sounds about right.