I just finished installing the lower rad hose engine heater in my BJ74 tonight. It turned out to be an easy install that ended very clean looking. The heater unit fit perfectly just under the spring clip that holds the lower rad hose against the fan shroud. This area also has the required 3" straight section and is angled upwards towards the engine block.
I'm heading to Kelowna next week for a few days. It's fairly warm there right now, but if it cools off siginificantly while I'm there and I get to use the engine heater, I'll let you guys know how it works.
The brand of my heater is Zerostart, a Canadian made product retailed at places like Canadian Tire. Mine is the 1.5" 600W model, and it regularly retails at Canadian Tire for around $39.99. I bought mine on sale last week for $32.