Dougie, you reminded me of a similar incident I had.
Driving through Germany a few years ago on the autobahn, doing about 130Km/hr I managed to hit a 2 foot section RSJ (T-Section profile). By the time I spotted it I only had a fraction of a second to respond and steered to have it pass under the middle of my fully loaded SW. But it hit and oil immediately covered the rear windscreen followed by the Stop Engine Low Oil Level warning. Fortunately I was able to coast into a nearby lay-by and stop the engine. On examination my aluminium sump guard was sliced through at the back with a big hole on the sump and brake pipes flattened.
Once back home we stripped the bottom end down in-situ, checked the big ends only and replaced the bent sump oil pick up pipe, then fitted the new very expensive sump, being careful not to wipe off the gasket paste here and there, this was a bit fiddly to align.
We used extra long ribe bits for the difficult to reach clutch end of the sump bolts.
Its been 6 years and apart from running the GQV between using the 156 SW its been 100%, no oil leaks or indication of bearing or cylinder related oil starvation issues With 178K miles and at least 35 to 40K of those since the RSJ incident.
The JTD engines I just love, they for me give very good reliability and economy, with it seems the added bonus of being tolerant to short term lubrication issues, just a shame the sump on the 5 stroker had to be inclined down and low.