Denis,
Your English is fine...much better than my German!
No girdle needed for a mild cruiser. An aluminum axle cover will lower the temperature of the gear oil but (most importantly) they LOOK REAL COOL!
You can find the W-27 style Olds axle covers at Fusicks, Year One, Supercars Unlimited, or even Ebay.
And welcome to classicoldsmobile!
C.J.