Patterned inner bore of shock bushing 90385-19003

[Eurasiaoverland]

My 60 came with OME suspension which needs new bushes. I ordered one OEM Toyota bushing 90385-19003 to see if it fits (it does), but find that it has a strange fluted internal bore.

What is the purpose of this pattern? Is it to allow the bush to better 'grip' the mounting plate pin? To add luibricant? Or just to allow water to sit there so the pin rusts out more quickly?

90385-19003 is used on the Heavy Duty Land Cruisers (60s, HD 70s, 80s 105s). 90385-19007 is a standard, solid bushing which is used on the Light Duty Land Cruisers / Prados / 4Runners which could be used interchangably.

 

[OSS]

Since OME shackles are greasable, their bushings are designed specifically for greasing. The Toyota shackles are not geasable by design and their associated Toyota bushings are not designed to be greased.
My vote: Use OME bushings with OME shackles

 

[Eurasiaoverland]

Since OME shackles are greasable, their bushings are designed specifically for greasing. The Toyota shackles are not geasable by design and their associated Toyota bushings are not designed to be greased.
My vote: Use OME bushings with OME shackles

The above pictured bushing is OEM Toyota and is from a shock absorber, not a leaf spring shackle.

 

[BurntToast]

The cross section effectively reduces the stiffness of the bushing but keeping its inner and outer geometry consistent. My guess is the desire with the patterned one is a softer or more compliant joint