I have a 10 Gage 600v cable with four aluminum conducters. How long can I make it for a 125v 30 amp camper plug? Also I'm having trouble with the male side of the plug if you had a picture of the old one that would be too cool. Thanks for your help.
You can't carry 30 amps on 10 AWG aluminum.
Check your wire length in a wire size calculator web site for whether you can carry 15 or 20 amps with that wire. Use a breaker with that amperage and use sockets appropriate to that amperage (NEMA 5-15 or 5-20).
You can't use a 30A RV receptacle (socket) with this cable, that can only be used on a 30A circuit. If you choose to use an adapter cable to connect your RV, well, the Electrical Code doesn't cover vehicles.
You must use connectors listed for aluminum wire. If they are not, you can pigtail copper onto then using a splice listed for aluminum-copper splices.
Make sure the aluminum wire is the newer AA-8000 series alloy and not the old 1300 series, which caused a lot of house fires in tne day. Code now requires 8000 series but I've never seen it in 10 gauge, so beware.
Do not use aluminum for a flexible cord. If you need flexibility, run the aluminum to a fixed receptacle, then run copper cordage from there. Cordage is special wire intended to be a flexible cord. Most often seen on appliances and extension cords. You want probably 12 AWG copper.
Attach 3 wires to the plug like this, you will not use one of the hots (e.g. the red). Wrap it with insulating tape or shrink tube or a wire nut so it doesn't short against anything,