How can I tell if my 2.25 has 3MB or 5MB?

Only 3rd post...so still feeling my way....I have a 1980 LWB S3 2.25 petrol, how can I tell if it has 3 main bearings or 5? The engine# (taken from the cylinder head?) is LRC5899CA (although the 'L' could be an 'E' and the 1st 'C' could be an 'O'....haven't had a reply to my earlier posts so keeping my fingers crossed on this one!

Engine numbers are on the block, behind the water pump, under the manifold. 5brg start with 361 or 364. The 5brg engines usually have a blanking plate on the front drivers side and the oil filler cap on the rocker cover in front of the breather cap.

if you look at block near sump you will see a ridge 2-3 inches up inline with dip stick hole if area between that and sump is flat its 3 brg if filled with cast cross pattern 5 brg

Big thank you...thanks for spotting the school boy error....found the engine# looks like (S?) 3650014....the oil filler cap is on the rocker cover forward of the breather cap....so that makes it a 5MB?

erc5899ca is metric cylinder head no also 3brg were buck egg blue 5 brg red

want to find out for sure. Take the sump off.