Since your Fleetwood is not a Forest River product and this forum is primarily for owners of Forest River products, you might not get specific information for your Mallard. I don't think any Forest River product had a manual slideout.
Possibly some member here may have owned one.
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Dan-Retired California Firefighter/EMT
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
4pt Equal-i-zer WDH and 1828lbs of payload capacity