Vaseline included?

All are good flying planes (340, 414, 421)

If possible, I'd go for 414A. No tip tanks, more fuel better performance.

Avoid the 421A at all costs (literally)

GTSIO-540 also have a 800-1400 TBO (depending on model). And it's geared.

(don't get me started)

The only issue with the 414A/421C is that with the wet wing, they fall under the Service Bulletin (SB) for the wing spar.

The tip tank models do not have the same wing and don't have that SB. Could be a costly ($70-80,000) thing if you're not careful with the aircraft that you potentially purchase. Be sure to read this post on AOPA before purchasing a 414A.

AOPA Online: Regulatory Brief -- FAA proposed twin Cessna wing spar ADs

Pre-buy.

I didn't see the 421 mentioned in the link but I'm sure it's likely included.

Cape air had a problem with a couple of their 402C's.

Mental note, it wasn't just the wet wing. The earlier models were a problem too.

I also remember several AD's concerning prop hubs cracking and exhaust leaks.
They were 50hour reoccuring. Since the exhaust goes right by the ring spar, a leak could mean a bad day.

(ask me how I know)

Well now I'm curious!!!....

I heard a story about a mechanic leaving a greasy rag in the wing of a 402.

Result: In-flight fire from the exhaust..... Is this what you are getting at Crimson???

If so....... Sounds scary

Had an exhaust failure in a 421. Manifold pressure went to ambient.
I pulled power to idle and landed. I was lucky, it only burnt a hole in the
cowling and damaged the engine mount.

If I had continued with reduced power, the engine would have slumped and
the prop contacting the fuselage (where I was).

Other incidents include an exhaust failure upstream of the turbo charger and
near the spar resulting in loss of wing.

If you are in a turbo powered twin Cessna and MP goes to ambient, the proper
procedure is a COMPLETE SHUTDOWN.

I was in a recurrent training event (for insurance) once, and the person told us if you have a wing fire, a la exhaust leak or failure, you have about 4 minutes to get on the ground, hopefully in one piece.

Daang I start flying one of these next week....lets hope i don't have any mechanical problems!

Trust your A&P. Hopefully they are very intimate with the airplane and it's systems. The place I work, we have 5 421's, varying years. Some are fractionally owned. Anyway, my boss has about 20k hours in 421's. His most trying time, according to him, was when he lost a turbocharger when he was over the Rockies. He made it down safely, of course. Lose a turbo on any airplane up high, hope the ground isn't too hard and lumpy.