I've got a 3845 ISR at the edge of my network.
ISP gives me E1, interfaced with V.35.
What network card/module and cable I should use for my ISR to connect E1 via v.35 interface on the PE hardware?
At first glance I look for WIC-1T or HWIC-4T, or HWIC-4A/S.
What for cable, I suppose that ISP is DCE, while my (H)WIC is DTE, so the cable will be CAB-SS-V35MT or
The E1 is handled by the external device.
Your router will only care about the serial connection from that device and the HWIC-1T will provide this for you.
As Paolo indicated, if you want to terminate the E1 on the router, then you need an E1 CSU/DSU,
http://www.cisco.com/en/US/prod/collateral/modules/ps5949/product_data_sheet0900aecd80710c77.html , not a serial interface as your original request indicates..
WIC-1T is End Of Sale and its replacement is HWIC-1T1
You will need a DTE cable CAB-SS-V35MT