The spare tire on the hood was used on other installation kits for the M38 Jeeps. Some that comes to mind are the recoiless rifle and the line layer variants. I have had a few of the wooden brackets with the spare tire mount, and the wood was more like a 1x4 or 1x3.
I have the ambulance modification instruction, but rather than go into detail, it just says to order two kits (the stretcher rack and the support kit) and follow the instructions contained within those kits.
I had an ex-ambulance M38 about a dozen years back, and it had some holes under the passenger side seat through the toolbox for ducting for a gas heater installation, along with a grill on the outside body going into the tool box.
See here for more info re the hood mounting:
http://www.mapleleafup.net/forums/sh...ight=ambulance
http://www.mapleleafup.net/forums/sh...996#post115996
There is this thread where I asked about some extra holes and brackets in an M38 I had. Peter Simondson said three holes on the sides of the body just behind the driver and codriver were for the stretcher racks. I see yours has the same 3 holes.
http://www.mapleleafup.net/forums/sh...ad.php?t=14896