Toyota will run its two TS040 HYBRIDs in low-downforce Le Mans configuration in this weekend's Spa World Endurance Championship event.
The Japanese manufacturer, which finished one-two in the Silverstone series opener earlier this month, has opted to gain experience with its Le Mans aero at Spa, a circuit that traditionally requires lower downforce levels than the British track.
Toyota technical director Pascal Vasselon said: "Spa is the final opportunity to race the low downforce-specification TS040 HYBRID before Le Mans and we will take this chance to further fine-tune the package.
"Silverstone was better suited to our high-downforce aero package, which is why we ran that on both cars.
"Spa's characteristics, combined with the limited track time before Le Mans, means it is a logical choice to run the low-downforce package."
Toyota ran its pair of TS040s in both high and low-downforce configuration at the official WEC test at Paul Ricard at the end of March after previously running with what was described as generic bodywork in its early-season testing.
Audi is running its two regular R18 e-tron quattros in high-downforce spec, but it will give its Le Mans aero a race debut on the additional third car to be raced by Oliver Jarvis, Filipe Albuquerque and Marco Bonanomi.
Porsche raced its 919 Hybrids at Silverstone at low-downforce levels as it gears up for its first bid for outright honours at Le Mans since 1998.