I would guess that it is most probably an "E" grill #88. However there appears to be part of a grill at the top of the stamp as well. The stamp appears to have some paper bits attached to it an looks rather dirty. I would first soak it and rub the back to dislodge any foreign material. If you use a press for drying do not apply to much pressure or it may flatten the grill points. I would next place some watermark detector fluid (lighter fluid) on top of your scanner, then place the stamp backside down in the fluid and put a Black plastic stock card on top and then scan. I find this is the best way to see the grill points. Hopefully this will show more clearly what we are looking at. It's possible that it could be a doubled grill. It is best to crop your scans. Getting rid of the useless area around the stamp will let you take a higher resolution scan using approximately the same amount memory.
re: Can anyone tell me what type of grill this is?
I would guess that it is most probably an "E" grill #88. However there appears to be part of a grill at the top of the stamp as well. The stamp appears to have some paper bits attached to it an looks rather dirty. I would first soak it and rub the back to dislodge any foreign material. If you use a press for drying do not apply to much pressure or it may flatten the grill points. I would next place some watermark detector fluid (lighter fluid) on top of your scanner, then place the stamp backside down in the fluid and put a Black plastic stock card on top and then scan. I find this is the best way to see the grill points. Hopefully this will show more clearly what we are looking at. It's possible that it could be a doubled grill. It is best to crop your scans. Getting rid of the useless area around the stamp will let you take a higher resolution scan using approximately the same amount memory.