How long should it take for a prior service CPL from the Marines to make SGT in the Army?

Stay squared away, care about what you are doing, lead from the front and set the esample at all times and you will move up very quickly

Hey CPL Blane the Army has no specific MOS as an RTO. It is an additional duty that anyone can be assigned. Radios are called GPU General Purpose User equipment, everyone has to be able to talk on them. There was one once in the 1970s called 05B but long ago deleted. If I had to guess what MOS most closely fits the job now days it is 25U Signal Systems Support Specialist. You do get training on RTO but your real job is performing Organizational Level maintenance (fixing) on any Commo/Signal equipment assigned to your unit. If it is above Org maint level you do all the paperwork, transport, turnin, maintain status reports and files to higher and set up accounts for Direct Support Maint Accounts for Signal Equipment. Mostly SINCGARS radios and phones and computers. What type equipment depends largely on the type of unit. An light Infantry Company will have vast amounts of handheld Comms, Mech Inf and Armor will have complicated track mounted systems, Aviation will have mostly vehicular stuff aircraft are maintained by Avionics personel not you. Warning you better have some computer skills because that is your job also. To answer your question about promotions, they have high cutoff scores so, it mostly depends on your skill and abilities if you are in the top 10% SGT will take about two years or more. The lower your skills the longer it takes, up to 4 or 5 years. Since the reorganization of Signal BNs into Brigade Combat teams promotion above SSG is very hard. To MSG nearly impossible, less than 1% of the 25U force makes E-8/MSG there are just so few slots now.

You can actually make that as a part of your enlistment. There are ways of making the rank of E-5 along with your signing of your enlistment papers. The thing to do is to contact the Recruiter and see. You might have to take a Correspondence Course to get the Rank.