I've been searching and no one has covered this yet. I have an obd2 b18b usdm block with b16 head and i was wondering if its POSSIBLE to install an oem breather box in the back of the b18b block? I believe there is a hole where the freeze plug is, doesnt it plug in there in the obd1 version of this block?

 

If I'm not mistaken, that hole is closed on the later b18b1, not a freeze plug. The best course of action is to order the washers and plugs from the back side of a Prelude block and thread them in the back of the block to vent to a can.