Agitators For WP Built Super Capacity Washers
Both WP and KM started out with extra large fined Bakelite agitators in their frist SC BD washers, KM had a huge straight vane and WP used a bigger version of there regular Surgilator that Glen posted above.
In 1969 when WP made the change to the much more durable Polypropylene plastic for agitators the new Surgilator for WPs SCWs was just like the regular Surgilator only taller, and for the KM SCWs they made a taller super Roto-Swril in either gold or white PP.
After this time both regular and SCWs used the same agitators for a number of years till Sears introduced the Dual-Action Agitator around 1976 and WP introduced the Double Duty Surgilator a couple years later for WPs SCWs.
In my hi-bread [ extra fast spinning ] 1971 LKM I used the taller white PP Surgilator agitator and it worked very well for many years.
With the orignal Bakelite agitators there was some speculation that the huge agitators put too much load on the transmissions, there were certainly problems with cracked and broken Bakelite agitators in these washers and WP-KM soon only supplied the newer PP agitators as replacements.
We have at the museum a fully restored orignal KM 518 SCW, it has my Stainless Steel center post outer sleeve upgrade and still has the orignal Bakelite three vane agitator.
IMEO these were the largest capacity TL washers ever built for home through the early 80s, however a SC DD WP built washer with a Dual Action agitator will easily wash as large a load as these early SCBD washers did, all these WP built washers had Norge, GE and Frigidaire 1-18s beat in capacity for sure and I will not even mention those little washers from Newton Iowa, LOL.