6.5 L possible blown head gasket
 

I've got a 1994 Chevy c3500 wrecker that actively tows. Pulling out of a parking lot after a tow in and white smoke starts blowing out the tailpipe. Of course it overheated on the way home. Coolant leaking out of the overfill. Pulled over in a parking lot, let it cool down so I could get it the mile home. Added coolant before I pulled out of the lot. On the way home the temp rose and then dropped real quick... was thinking it was a thermostat issue so replaced that as it was a cheap and easy possible fix.

I was hoping that this isn't a blown head gasket, as it's my livelihood and I can't afford this downtime... but it sure is seeming like that's what it is.

Can anyone give me some solid advice on what my next steps should be to determine if this is for certain a head gasket issue?

Top radiator hose is rock solid on cold start, white smoke out of tailpipe, coolant just pours out of the overfill when it's added.

I need to start tearing apart ASAP if this is the case, as I need to get this truck back on the road before I start losing business so if anyone has input I would greatly appreciate it.

Oh yeah, its head gasket time...…….
Those 6.5s don't take heat all that well.
Its almost worth having a complete spare engine handy, that way ya just pull out the old and slip in the new, then repair the old at a more convenient time. Been there, done that...many years ago. Good thing those engines don't break the bank.