Here you go. I will just put up a picture as there are a few numbers on there. They were in a big row of drawers for "Grade 8" and come in a two pack for like $2.38 or something like that.

 

Land Rover propshaft bolts are Grade 5 which is what they should be replaced with. Replacing them with grade 8 is a waste of money.

More importantly, you should never mix grades of bolts and nuts. i.e., using a higher grade nut on a lower grade bolt and vice versa. The higher grade part can cause the threads to strip on the lower grade part.
If you're replacing with grade nuts use grade 8 bolts, which means pulling the output flange to remove the captive bolts.

Finally, propshaft bolts/nuts are a very critical fastener and should not be over torqued as it can stretch them beyond their yield point and lead to early failure. This is very easy to do using an impact wrench.

 

Why would LR use grade 5 bolts? Just curious... there must be a reason.
Edit: The reason might be cost savings... "manufacturers use what it needs to be safe and nothing more"
http://www.rockcrawler.com/techrepor...ners/index.asp

 

Fine thread Grade 5 nylocks are a lot easier to source as well.
In 35 years of not light duty Land Rover use, I've never broken a propshaft bolt and I've always used grade 5.

 

Gotcha, something else is going to break before you shear those bolts.

 

Very true. If I was pushing 400HP I might think about switching them!