[Sasha]

Just a shout out to Brian at Tiara who responded to my email immediately and gave me the original part information.  In case anyone else can use it here it is:
Tiara part # 5353720 ACTUATOR DM12-20, HATCH LIFT
Note that there is a 20A5 and a 20B5, and the correct one is the heavier B5.  Thomson Linear is the supplier.

What other company other than Tiara takes such good care of their 25 year old products?

?  No one.

Is it safe to assume that on my 1995 36 open which has the Acme screw Drive (based on my read of the Warner Electric P-264-M manual for DM series) would use a DM12-24A5  since the bolt to bolt dimension "B" is 24.32 inches with an "A" dimension of an 18" stroke. I cant read the decal except that the max amps are 15. Also is there a number or letters after the 24XX ? One supplier told me there is. 
My catalog does not show a model a B series model with a
24.32" B dimension and a stroke of 18".