On my 49 GMC the overflow tube exits out the very top of the reservoir, runs along the top to the left side where it turns down inside of the radiator mounting frame and routes down to the bottom where it'll dump overflow on or around the front cross member.
If you pull the top rad mount you'll see it and can access it.
re. coolant level and overflow tank. I recommend them. These AD's when stock like the coolant level an inch or so below full and if you fill it to the top they'll generally whiz it out until the level stabilizes where it likes it. Baring hot days and alot of idling they'll be happy there and you'll only occasionally have to top it off. If it runs little hot it'll whiz it out more frequently and need coolant added more frequently.
I've added overflow tanks to both my AD's and I've found that I can top the radiators off and haven't had to add coolant since. The coolant that whizzes out to the overflow tank gets sucked back in when it cools off. Outta site outta mind.....
So it's 6 of this and a 1/2 dozen of the other.
Good luck
Dave
