Someone posted this thread and it worked for me back in July. The GM rebate offer is active again for wiper blades purchased between now and 12/31/19. New items added are AC Delco air & cabin filters. This rebate program is not limited to just Rockauto, but the original post had a way to get 6 wiper blades for free basically and it worked for me again yesterday.
Original SD post.
GM rebate website.
discount code for 5% expires 1/5/2020
Original opening post from previous SD alert in text format:
rockauto.com has ACDELCO Advantage All-Season Metal Blades on sale for $2.80.
Car Part Catalog: https://www.rockauto.com/en/catalog/
Go to rockauto.com and select your vehicle. Scroll down to last category, "Wiper & Washer". Click the + sign to expand category and then select "Wiper Blades". Then it's probably easiest to use your browser's Find in Page for ACDELCO
QA Note: Look for the ACDelco Wiper Blades that are $2.80
Combined with this $5 Mail In Rebate on ACDelco GM Wiper Blade between 6/1/2019 and 7/31/2019 - Limit 6
QA Note: Digital Rebate Form Link: https://www.gmpartsrebates.com/vehicles.asp
(Hit the Get Started button under GM Genuine Parts/AC Delco, then look for "ACDelco Wiper Blades" box, and hit the "Submit" button under that)
and a 5% discount code from SD's RockAuto.com - 5% discount code megathread
The 5% discount code is entered in the "How Did You Hear About Us?" field.
If you pay with Discover Card using Paypal you'll earn another 5% cashback.
Included is my order confirmation for $23.95 including FedEx Ground to S. FL at $7.99.
UPDATE. Word of Caution : The online rebate submission page asks for a VIN number. It only accepts 17 character VINS which have been in use since 1981. If your vehicle is 1980 or earlier, use someone else's.