Because of the number of Renault Type 336 & 354 transaxles
  that are showing up on eBay, (and are being listed as suitable
  for use in the Lotus Europa), some points should be clarified.

 Although the Lotus Europa used a Renault Type 336 Transaxle,
 it was a HEAVILY MODIFIED unit.

 First: 
   The Lotus unit was modified by changing the position of
 the Crown Wheel to the other side of the case.
 This required extensive machining to the inside of the case.
 This was done because the Lotus Europa is a Mid-engine Rear
 Wheel drive car, with the engine in FRONT of the transmission,
 and the Renault R16, (from which the Type 336 transmission
 came), is a Front wheel Drive car, with the engine BEHIND the
 transmission.

 What this means is that if you try to use a Renault transmission
 in the Lotus Europa, you will have only ONE (1) forward gear,
 and FOUR (4) REVERSE SPEEDS!

 Second:
  The engine that was used in the Lotus Europa was HIGHLY
MODIFIED, (increased from 53 to 87 horsepower), by Lotus.
To take advantage of the increased horsepower, special gears 
(made by Hewland Engineering, of Racing Transmissions fame),
were cut and heat-treated.
The gear ratio was also changed to suit the higher rev range of
the engine.

  Even if one went through the expense of machining the inside
of a Type 336 case so that the Crown Wheel could be reversed,
the stock Renault gears would not last very long when used in
a Europa with its greatly increased horsepower.

 In short, only the Type 336 (4 spd.), Type 354 (Twin-cam 4 spd.),
and the Type 365 (Twin-cam 5 spd.) transaxles that are built by
Lotus should be used in any Lotus Europa, especially if one
expects to get all of the performance that these cars are capable
of.

  The Renault transmissions are fairly easy to spot on eBay, as
they use a completely different gear linkage then the one used
by Lotus.
Also, many times they will have the Renault mounting hardware
still attached.
If a Seller still insists that the tranny can be used in a Lotus, get
a guarantee in writing, that you can return it for a refund,
(including the Shipping Charges), if your car goes slow in 1st
gear, and real fast in Reverse 1, R2, R3, and R4. 
                                                      .-------------------------------JMM