A later manual suggests removing the trans top cover and replacing it with a piece of cardboard to keep the dirt out, giving extra room when the trans goes by the hole in the firewall. And pulling the engine and trans as a unit. I think this was on a task force truck. I have done the same on an AD truck. I have puled many engines and found that if you have equipment to handle the weight and you have room in front of the truck, it's a lot easier to pull both as a unit. Pulling the trans from underneath was never fun and fifty years later nearly impossible given the shape of the case and my age. On my AD I long ago cut welds on the top cross support and drilled it for bolts to reassemble. I'm not sure how much you would gain on a Deco truck by doing that. I like the remove-the-front-clip idea. Mind you I have not worked on Deco trucks.
Tilting the whole shebang to get it out of the engine compartment with the radiator support in place I think is dangerous. I also would not pull the engine by the rocker shaft bolts. You are lifting 700+ pounds with two 3/8 bolts. Then, if you pull the trans too that's another 180 or so pounds. That makes me uncomfortable. Go buy some *forged* eye bolts to replace two head bolts the hook on to those.
