Pat,
I believe they are all dual motors.
And, I have had the unfortunate experience of having to become a semi-expert on BEEPs.
The ones made by Taylor Trucks, O-Line Reproductions, and Aristo generally run well.
The ones made by RMT up until mid 2015 do not run well at all. At their fastest speed, they travel at what most would call a low medium speed.
In 2015, RMT upgraded the circuit board to fix a lot of the problems, and this continued until the production ceased. These upgraded units run much much better.
You can tell the old RMT from the upgraded RMTs by looking at the handrails. The old ones all have "chrome" handguards. The upgraded ones have different colored painted handrails, depending on the rail line of the shell.
Also, in the later years, RMT started making "holiday" themed Beeps, such as the Christmas Snowflake model and the Halloween model, and these are also the upgraded ones.
I think that if you go to the research function of this Board, and search BEEPs, you will probably find the post that I put up about 3 months ago, with a complete list of all of the RMT upgraded models, by rail name and engine number. (They even made a red "Atomic Energy" Beep.)
My advice is do not buy one of the earlier RMTs Beeps. And whatever Beep you want to buy , make sure you watch it run at full speed on a test track. These are great little unique diesels, but they can be burned or damaged.
And, don't rule out buying one of the Halloween Beeps, which you can still find NIB, and switching the shell to a real rail line shell. RMT liquidated all of its remaining Beep stuff about 3 months ago, and they dumped lots and lots of leftover new shells on the market. Just check on Ebay. (They also dumped a lot of old inventory of the original poor circuit board Beeps on the market as well. So watch out, these are all over Ebay as NIB units.)
And oh, also be aware that there are two "issues" with the couplers.
First, if you use the Beep on 031 curves, the coupler arm, as it swings to each side, with hit the low sides of the plastic engine shell. So, you have to take a tool and cut back the engine shell about 3/8 inch on each side of the front and rear couplers.
Second, the couplers are really stiff, And I mean REALLY stiff. They will derail just about any car you put behind them unless you really weigh down the front of the car. I tried to "weaken" the coupler springs by taping the couplers to one side or the other, and leaving them for a month. No help. They springs were still stiff and derailing cars. I recently solved this problem by simply unscrewing the coupler screw underneath the body, disassembling the coupler (only 3 parts), looping the circular part of the spring over a small screwdriver shaft, clamping the screwdriver in a vise, and then grabbing each protruding horizontal protruding side of the spring (two sides) and bending the back really hard with my hands, until I had bent them back about an extra 15 to 20 degrees. After re-assembly, the coupler was a little mushy as to returning to dead center, but I have had no more derailing issues.
Finally, you may have to remove one or both of the friction tires on the Beep to get it to pass over Lionel 031 switches without stalling. These diesels are really short, and the little side to side uneveness cause by the thickness of the tire will cause the Beep to rock to one side as it goes over the switch, and lose contact with the outside (neutral) rail. In my case with one of my Beeps, it came to a complete standstill and would not move.
More than you ever wanted to know, but I hope this helps.
Mannyrock
