On the V6 Sprinter you DO have an access problem, no manifolds need to come off, and the glow plugs can be had for $20. The intake air box and plastic engine cover has to come off. For cylinders 1,2, and 3 another plastic cover has to come off. For 5 and 6, the turbocharger outlet plumbing and resonator have to come off, followed by repositioning of a wiring harness. The glow plug electrical connectors are difficult to remove, easier with a special tool. Once this is all done, if you have the Mercedes glow plug tool, or wobble extensions, THEN it's a 5 minute job. I've not heard of stripped plugs, but sheared-off plugs is an all-too-common occurance.