TABLE I.  STANDARD THREADS - from "Machinery's Handbook", 21st Ed.  American or Unified National
Coarse and Fine (UNC, UNF), US Pipe (USP).  British Standard Whitworth, Fine, Pipe or Association (BSW, 
BSF, BSP, BA).  Metric: French Standard, Fine Thread and International Standard (ISO)
BSW, BSF, BSP BA and French Standard Metric is found in T Series cars (late TDs & TFs use UNF on the rear                   
axle and for wheel studs).  Whitworth (W) or BSF marked wrenches fit all fasteners except UNF on T Series cars.
SIZE Dia.  UNC BSW UNF BSF BA French Std. Fine metric ISO Metric
  (In.) TPI TPI TPI TPI TPI mm TPI mm TPI mm TPI mm
#2 0.0860 56 64
8BA 0.0866 59.1 0.43
6BA 0.1102         47.8 0.53            
#4 0.1120 40 48
3mm 0.1181             50.8 0.50 72.5 0.35 50.8 0.50
#5 0.1250 40 44
1/8 0.1250 40 40 * *                
5BA 0.1260 43.0 0.59
3.5mm 0.1378             * * 72.5 0.35 42.3 0.60
#6 0.1380 32 40
4BA 0.1417         38.5 0.66            
5/32 0.1563 * 32 * *                
4mm 0.1575 33.9 0.75 50.8 0.50 36.3 0.70
3BA 0.1614         34.8 0.73            
#8 0.1640 32 36
2BA 0.1850         31.4 0.81            
3/16 0.1875 24 24 32 32
#10 0.1900 24   32                  
5mm 0.1968 33.9 0.75 50.8 0.50 31.8 0.80
1BA 0.2090         28.2 0.93            
#12 0.2160 24 28
7/32 0.2188 * * * 28
6mm 0.2362             25.4 1.0 33.9 0.75 25.4 1.0
0BA 0.2362 25.4 1.00
#14 0.2420 24   *                  
1/4 0.2500 20 20 28 26
5/16 0.3125 18 18 24 22                
8mm 0.3150 25.4 1.0 25.4 1.0 20.4 1.25
3/8 0.3750 16 16 24 20                
1/8 BSP 0.3830    28 Straight thread
1/8 USP 0.3970          27 Straight thread            
10mm 0.3937 16.9 1.5 25.4 1.0 16.9 1.5
7/16 0.4375 14 14 20 18                
12mm 0.4725             16.9 1.5 16.9 1.5 14.5 1.75
1/2 0.5000 13 12 20 16                
1/4 BSP 0.5180    19 Straight thread
1/4 USP 0.5260          18 Straight thread            
14mm 0.5515 12.7 2.0 16.9 1.5 12.7 2.0
9/16 0.5625 12 12 18 16                
5/8 0.6250 11 11 18 14                
3/8 BSP 0.6560    19 Straight thread
3/8 USP 0.6620    18 Straight thread
1/2 BSP 0.8250          14 Straight thread            
1/2 USP 0.8230          14 Straight thread