Our 7200 is currently etherchanneled to a 3750 stack(and working fine).

It *will* allow you to configure a port into any channel 1-64:

router(config)#int gig0/0

router(config-if)#channel-group ?

<1-64> Channel group number

But while in normal enable mode, will only let you check status of group 1-6:

router#sh etherchannel ?

<1-6> Channel group number

brief Brief information

detail Detail information

load-balance Load-balance/frame-distribution scheme among ports in port-channel

port Port information

port-channel Port-channel information

summary One-line summary per channel-group

router#sh etherchannel 10

^

% Invalid input detected at '^' marker.

Has anyone seen this before?

It is currently working just fine using channel ID 10, but annoying because I cannot use the normal show command I am used to using.