Help identifying ASSA padlock

Hello gang. I was wondering if anyone would be able to give me any info regarding this ASSA padlock that I found this week at a local locksmith shop. For a long time I've had a passing interest in high- security locks and their applications, but only recently have decided to start collecting padlocks and gaining some real knowledge about their operation.

So I came across this lock, and I can't seem to find any info about it anywhere. The only reference I've found is a single image in "Locksmithing: From Apprentice to Master". The only identifying markings on the lock itself are "ASSA 4-5". Here is a picture of the lock:

Can anyone point me to info about the model type, dates of production, cylinder type and function, construction details, value, etc? It appears to be an older version of the current 4-5 lock, which is of a very different shrouded design.

And finally, I purchased a nearly identical lock marked "ASSA 3" that's a bit smaller. The keyway appears to be a little different and there are minor construction differences, but it looks like the little brother of the one in the above picture. I have the same questions regarding that one, if anyone has any info! The 4-5 lock is still sitting on the counter at the locksmith shop, so I might pick that one up too if I can find some good info about it first, hence my post here.

Thanks for your help!