If the cam and towers broke, chances are the pistons and rods are just fine -- this was the case with my brother's 300D. He busted the crank, and it blew the cam towers off, we even re-used the cam!

You can fish the chain up from underneath, but you are going to have to pull the IP and injection timer to do it. Much easier with the engine out, although you can do it with the engine in place, just more work. Pull vac pump and timer and IP, then use a wire to pull the chain up from the bottom on both sides, then up through the upper chain guides. Set crank to TDC on #1, then set cam to TDC on #1. Wire chain up, then install injection timer. Install chain on cam gear and install the "master linK" but don't swage it. Set engine to 24 (or 26) degrees BTDC and install IP and check engine and IP timing, then swage chain link.

This is all easier with the engine on a stand...

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!