Later-model 261's could be set up for either bypass or full flow oil filters. Of course, the best option is to use both- - - -full flow to strain out the rocks, marbles, and bowling balls, and a bypass filter to do a good job of cleaning up the oil!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!