Thanks for the nice comments.
On your 5 cylinder turbodiesel, you should remove the cam cover and the fan. Then, rotate the engine using a socket on the crankshaft until the timing marks on the cam and cam tower align (similar to what my pictures show for the V8). Then take a look at the degree wheel on the cranshaft and see how many degrees past zero it is. (If you have difficulty getting at the fourth fan retaining bolt, turn the fan with a 22mm socket on the nut on the power steering pump. You have to loosen all four and remove three to get the fan out).
On my 300SD (1983) I replaced the chain at 7 degrees of indicated 'stretch' at a very young 100k miles.. Now, older and wiser, I would first replace the chain tensioner and see what the indicated stretch is then. My SD has a stepped tensioner (unlike the sprung piston in the V8s). Replacement is easy. If, after replacement, the chain still shows over 7-8 degrees of stretch, I would change it.
If your guides/tensioner/chain are very worn, you will hear the chain rattle against the engine casing when first started. On the V8s, failure usually results from a guide getting slapped and broken by the chain, riding up between the chain and the cam gear and forcing the chain to skip a tooth, with expensive damage to the top end. Some suggest diesels are also prone to camshaft fracture - maybe caused by the higher compression.
The in-line 5 has one big advantage in this regard over the V8 - a shorter chain with a simple loop path, rather than the tortuous direction reversing path in the V8, so it tends to wear chain guides less. At your mileage, I would consider changing the upper guides as well - they are cheap.
The process is similar to that for the V8 engines.
I did crimp the chain on the I5 as the tool could be rented in those days. Now, as I do not want to spend the $300+ on a rarely used tool, I would seek to borrow it or would use a clip.