The difference between a traditional dubbel and a tripel recipe-wise is maybe 2 lbs extra pilsner malt maybe a touch of munich and dark candy syrup vs light. (new world versions often have some darker caramel malts/special B etc)
Having never tasted the beer..... generic starting amberish base
Pilsner (#based on your efficiency or Pilsner/extra light DME)
1lb munich
0.5lb special B
1.5lb table sugar
0.5 lb dark syrup (not the amber rocks)
Hop to 25IBU or so with noble hops with no more than 1 oz in the 0-15 minute range
Belgian yeast - no idea what they used, but all are tasty - started mid 60's and ramped into the 70's