Here's a p24 oscillator that one of my drifter searches found:

`x = 16, y = 15, rule = B3/S23`

5bo$5b3o$8bo$7bo3bo$3b2obo3bobo$2bobob2ob2obo$bo2bo8b2o$bobob8o2bo$2ob

obo8b2o$3bobobob2o$3bobobobobo$4b2obo3bo$6bob3o$6bobo$7bo!

The upper right part is p6. Changing just one cell makes the upper part stable and the lower part p7:

`x = 16, y = 15, rule = B3/S23`

5bo$5b3o$8bo$7bo3bo$3b2obo3bobo$2bobob5obo$bo2bo8b2o$bobob8o2bo$2obobo

8b2o$3bobobob2o$3bobobobobo$4b2obo3bo$6bob3o$6bobo$7bo!

With a smaller stator, this p7 is already known. The p24 is also related to 2 other known oscillators, with periods 10 and 17. Here all 4 are shown; note that the lower left part of the p24 is like the p7 in gens 0-16, like the p10 in gens 14-26, and like the p17 in gens 7-33. Basically, the p17 does a p7 cycle and a p10 cycle, and the p24 does 2 p7 cycles and a p10 cycle. I wonder if there are any larger period oscillators like these.

`x = 80, y = 65, rule = B3/S23`

36bob2o$36b2obo$40b2o$41bo$40bo$40b2o$38b2o$39bo$38bo$38b2o$36b2o$37bo

$36bo$36b2o4$40b2o$40bo$42bo$38b5o$37bo$33b2obob5o$33b2obobo4bobo$36bo

bobobob2o$36bobobobo$37b2obobo$39bobo$39bo$38b2o4$38bo$2o4b2obo28b3o

29b2o2bob2o$bo4bob2o12b2o17bo15bo13bo2b2obo$o3b2o4b2o10bo17bo3bo11bobo

11bo7b2o$2o2bo5bo12bo12b2obo3bobo10bobo3b2o6b2o7bo$5bo5bo8b3obo10bobob

2ob2obo7b2obob2o3bo14bo$2o2b2o4b2o7bo4bo9bo2bo8b2o6bobo4bobob2o3b2o6b

2o$bo2bo5bo4b2obob5obo7bobob8o2bo3bo2bobobobobo2bo4bo4b2o$o4bo5bo3b2ob

o6bobo5b2obobo8b2o3b2obobo4bobo5bo6bo$2o2b2o4b2o6bo2b4o2bo8bobobob2o

11bobo2b2o2b2o4b2o4bo$4bo5bo7bo3bobobo9bobobobobo10bobo3bobo12b2o$2o3b

o5bo7b2obo2bo11b2obo3bo11b2obobobo6b2o2b2o$bo2b2o4b2o9bob2o14bob3o14bo

bobo8bo3bo$o5b2obo11bo17bobo16bobo9bo3bo$2o4bob2o10b2o18bo18b2o9b2o2b

2o4$34b2obo4b2o4b2o$34bob2o5bo5bo$38b2o2bo5bo$38bo3b2o4b2o$39bo4bob2o$

38b2o4b2obo$34b2obo10b2o$34bob2o11bo$32b2o14bo$32bo15b2o$33bo$32b2o$

34b2obo10b2o$34bob2o10b2o!

David Buckingham found the p7 (unnamed) and p10 (

42P10.1) in the early 1970s; I found the p17 (

54P17.1) in 1997.