7" air filter instruction tag

[48hdbob1]

I have two different instruction tags on chromed steel 7" filter covers and don't know when these changed. One reads "Every 500 miles or under extremely dusty conditions, every 100 miles". The other reads "Once a day under very dusty service conditions, or at intervals not exceeding 1000 miles or one month under any service conditions".

[bmh]

The second tag is the one that appears on stainless covers used from 49-55. I am fairly certain it was used on 48 machines with chrome covers as well. I have pics of an original late 46 and it has the earlier tag that reads every 500 miles..... Don't know what they did in 47.

[48hdbob1]

Thanks!!-Bob