Hey Doc I guess we are the only ones still going at it this late. Not sure about your car . Page C8 of the 308GT4 manual shows the position right above the starter but below the cylinder head. Maybe you could contort from underneath to reach it better then from the side. But it is easy enough to try from the side first I guess. Remeber it is under the front cylinder head so you will be reaching around the front of the engine.
pull right rear tire off, remove fender liner, stick hand into wheel well you should be able to see it on the block. edit: thats for the 308GTS anyway, at least thats what i remember, might be different from the GT4.
Not sure if the GT4 is the same as the 308, but, there is a cover plate at the front underside of the 308 where a lot of the cooling plumbing comes together. That is also another required drain area as well if you are trying to purge all old coolant from the system.
Dont know how to follow that last post, but here goes. I just did this same "all hoses" replacement and I would really recommend getting a cooling system checker and using it to check for leaks. I filled the system and then just kept tweaking the 30-40 hose clamps until it would hold 15 PSI overnight. (I think I have this one http://www.sears.com/craftsman-cooling-system-pressure-tester/p-00946342000P?prdNo=1 ) and it fit the catch tank on the GT4, but theres nothing special about that cap. Much easier than dealing with hot fluid and a running engine. You can bring the pressure up gently to reduce the amount of mess, and can hear little hisses.. I also think it helped purge the system of air.
