[rescue] Sun E4K CPU Upgrade

[Richard]

Hi Folks

Looking for experience/guidance on CPU upgrade for my E4K.

My E4K currently has 
- 3xCPU boards with a total of 6x 336Mhz CPU's on board. 
- I have 2x new CPU boards coming and they have 400Mhz CPU already on board.
- I also have an additional 4x 400Mhz CPU's on the shelf. 

I am therefore thinking/ looking to purchase 2 more 400Mhz CPU's so I can upgrade all CPU's to the 400Mhz versions.

when I look at the parts list for the E4K http://shrubbery.net/~heas/sun-feh-2_1/Systems/4u-Server/E4000.html 

I see there are a number of options

400MHz UltraSPARC II Module
 501-4995
 501-5425
 501-5585
 501-5235
 501-5661
 501-5762

when I go to eBay I have found some different numbers for the CPU Module i.e. 501-6009 or 501-5838 .

I further note that the compatibility statements exist for each CPU such as this for 501-5235

Clock 501-2975 is not supported.
The E6000 and E6500 require Clock 501-5365 for a 5:1 clock ratio.
The E3x00, E4x00, and E5x00 require Clock 501-5365 for a 5:1 clock ratio if 84MHz system boards are installed.
Clock 501-4286 or 501-4946 is supported in the E3x00, E4x00, and E5x00 if the centerplane and all system boards are 100MHz.
Clock 501-5365 is supported if 84MHz or 100MHz system boards are installed in the E3x00, E4x00, and E5x00.

Is it just a mater of inventorying my machine and working out which modules are compatible with what is in there already or is there an easier way?

Appreciate thoughts/insights.

Regards

Richard