Discovery 200tdi conversion - additional bolts into ladder frame?

Hi all. I'm picking up a discovery 200 this Thursday, just a quick question that someone who has done this can answer:
Both Glencoyne and Steve Parkers recommend drilling and tapping the flywheel housing to bolt through into the ladder frame.
They say it will likely leak if this isn't done. Anyone have experience of not doing this and not having an oil leak between the block and housing?
Does a defender 200 tdi bellhousing have these bolts through into the ladder frame?

I feel like I have been surfing about this for years - probably have lol. Hard to tell from the scan of the parts manual, but I think the original defender 200 tdi flywheel housing does have the bolts through the ladder frame. To counter this, all the conversion blogs seem to have not bothered, just swapped the TD or NA bell housing, or even adapted the disco one. I'm leaning towards the latter, which means removing a couple of dowels and drilling the bellhousing.

Not sure on your defender but when I stuck the disco tdi in my series I countersunk the bottom 4 holes and fitted long allen key headed bolts through and into the ladder. think there was also 4 holes to tap out to M10 and a dowel to remove but it was a while ago now, none of it hard work at all, been in for 5/6 yrs and only issues was pattern rear crank seal blew out, no leaks from bottom of flywheel housing or ladder assy.

Terriann website has an excellent write up of sticking a 200 into a 109 s2 by Glen Anderson, top quality job

Thanks Lynall, you seem to be one of the few who have fitted the long allen bolts. I think I will leave the disco flywheel housing in place and modify the N/A bell housing to fit.

I only did it after reading the stories of oil leaks and Glens write up as we all know removing engines for something we should have done in the first place is a real pita! not that Ive done anything that stupid you understand!