If you followed the USFL in 1984, a subtle change took place during the middle of the season.  The Pittsburgh Maulers had to change their helmet logo/decal supposedly due to the fact that the orange/purple “Mauler” logo was difficult to see on TV.  At some point in the season the old logo was replaced with a logo that had a white outline around the “Mauler” on the decal.

Here are the differences:

Old logo:  http://www.geocities.com/usflmuseum/84misc/84pmaulersmisc.html

Changed logo:  http://www.misterhabs.com/helmets.htm

If anyone from the Maulers or USFL offices ever finds this post then please leave a comment on the specifics of when/why the exact change was made.  Thanks in advance!

If you are considering collecting USFL memorabilia and merchandise due to its scarcity then take note of this fan! Evidently, he has taken USFL memorabilia collecting to a new level. Just a quick glance of the photos will show you that he has some unique items which may be difficult, if not impossible, to find on the open market.
http://www.geocities.com/usflmuseum/usflfeatured.html

Here is another website which does a good job of detailing the USFL helmets from all of the seasons.  No mentions of any changes to helmet designs for the 1986 Fall season are made; and any such changes are suspect depending on which sources of information you read.

http://www.thornbird.net/football/helmets/USFL/USFL.htm

Here is a terrific website which breaks down the changes in the helmets used by USFL teams, including season-by-season changes.  It also shows the intra-season intricacies such as when the 1984 Pittsburgh Maulers added a white outline to their helmets during the season to help add clarity for television viewers.

http://www.misterhabs.com/usfl.htm