78 Spitfire Dippy Stick question

[Metwrench@aol.com]

Fellows !

I have a technical question....
I just got done a motor overhaul. The motor had a Dipstick attached to the 
drain plug instead of in the block. Has anyone else seen this setup ?

Question 1 : Can this be replaced by the "in the block" dipstick ?

Question 2 : Is the Drain plug available for this type setup ? ( brass plug, 
very odd because it houses the dipstick banjo )

Question 3 : Why and when was this done ? My 80 and 75 did not have this 
setup.

John S
80 -8
76-6
80 Spitty